Use the i2c protocol to reduce the occupation of I/O ports, making it easier to add to the project, and less wiring is more beautiful. | Commonly used in: Internet of things, DIY project, home animation, smartbuilding, maker's DIY project. | Compatible with all current development boards, such as Arduino, Raspberry pi, Tinkerboard, Nano pi, Banana pi, stm32 and so on | With a potentiometer used to adjust backlight (Color: Blue) and contrast.Power supply: 5v and I2C address is: 0x27 Module dimension: 80mm x 35mm x 11mm | Wiki:http://wiki.52pi.com/index.php?title=1602_Serial_LCD_Module_Display_SKU:Z-0234
Well Packaged - With a storage box for 102pcs heatsinks, it perfectly divides the heat sinks into 17 categories. | Multiple applications - It can Cool Raspberry Pi VRM VRAM CPU GPU Small IC Laptop 3D Printers Stepper Motor Modules TMC2130 TMC2100 A4988 DRV8825 TMC2208. Multiple sizes, multiple application scenarios. | Good heat dissipation effect - Various Aluminum and Copper heat sinks with Thermal Conductive Adhesive Tape for cooling Raspberry Pi 4 and electronics components. | Different Sizes - 102pcs multicolor heatsinks in different sizes contains 92pcs aluminum heatsink and 10pcs copper heatsink. | Package Includes: 102pcs multicolor heatsinks, 1x Storage Box.
Compatible with Pi4/Pi3B+/3B: GeeekPi Raspberry Pi 4 Power Supply USB C Power Supply is specially designed and tested for the Raspberry Pi 4; With a Type-C to Micro USB power adapter for Raspberry Pi 3B+/3B. It's also compatible with Orange Pi 5 and Orange Pi 5B. | With Professional Certification: Raspberry Pi 4B Power Supply with UL Listed Certification, TUV and RoHS Certification; Input: 100-240V AC~50/60Hz; Output: 5V 4A 20W; Extended Cord: 120cm. | After repeated testing to provide the highest power stability High quality copper wire core, good conductivity, stable transmission, Inline Noise Filter. | With ON/OFF Switch: It's convenient for you to power on and power off your Raspberry Pi 4. | Multi-Protection Functions: Over voltage protection; Under voltage protection; Over temperature protection; Over current protection; Short circuit protection. | Package Includes: 1x 5V 4A US Plug Power Supply with ON/OFF Switch, 1x Adapter for Raspberry pi 3B+/3B
Compatibility - GeeekPi 27W USB C Power Supply is compatible with Raspberry Pi 5 4GB/8GB. | Power Delivery Support - The adapter is equipped with Power Delivery technology, allowing for fast and efficient charging of compatible devices. | Universal Compatibility - With an input voltage range of 100-240V and a frequency of 50/60Hz, this adapter is suitable for use worldwide, making it a travel-friendly power solution. | Compact and Portable - Designed for convenience, the compact form factor of the adapter makes it easy to carry, ensuring you have a reliable power source wherever you go. | Multiple Output Options - The adapter offers a variety of output voltage options, including 5.1V at 5A, 9.0V at 3.0A, 12.0V at 2.25A, and 15.0V at 1.8A, providing flexibility for different device requirements. | Safe and Reliable - Built-in safety features such as over-current protection, over-voltage protection, and short-circuit protection ensure the safety of your connected devices.
The 40pin header kit box is a full range of 40pin component boxes for electronic enthusiasts DIY. | Packing List: 2 * 2x20 Long Female Header (Pin Len: 12mm), 2 * 2x20 Long Female Header (Pin Len: 11mm), 2 * 2x20 in-line female row (Pin Len: 5.5mm), 2 * 2x20 straight Pin Header, 2 * 2x20 90 Degree Curved Pin Header, 2 * 2x20 90 Degree Curved Pin Header,1 * GPIO Edge Extension | Application: It can be used for Raspberry Pi pin expansion, and it can also be used for all 40pin pins. Occasion, such as Tinker board, jetson nano and other standard 40Pin equipment pin extensions, etc. | Stacking header for Raspberry Pi 4, Pi 3, Pi 2, Pi Model B+, Pi A+, Pi Zero, Pi Zero W, Pi Zero 2, Pi Zero W2
Size: 15*15*5mm / 0.59*0.59*0.2inches (L x W x H) | Pure Copper Material; with Thermal Conductive Adhesive Tape; with Strong Thermal Conductivity and Heat Dissipation. | Used for cooling various electronic components, such as Raspberry Pi/Orange Pi/Rock Pi/Tinker Board/PCB Board/Motherboard | Please tear off the thermal tape before sticking it.
【DeskPi RackMate T1】It's made of aluminum alloy and acrylic frame mini chassis which you can setup your own cluster or home assistant server. | 【10-inch width】The cabinet has a width of 10 inches, which is a relatively small size that saves space while accommodating sufficient equipment. With dimensions of 11x7.8x16 inches, it is suitable for small offices, home environments, and large enterprises looking to save space. | 【Open Design】The cabinet adopts an open design, allowing easy access to all devices inside. This design facilitates equipment installation and maintenance, aids in device cooling, and maintains optimal working conditions. | 【8U Standard】The cabinet has a height of 8U, which is a standard unit size. With 1U equaling 1.75 inches, 8U implies a height of 14 inches. | 【Translucent Design】Both sides are made of translucent acrylic, providing dust resistance and reduced weight. This design allows direct observation of the cabinet's interior, and users can add ambient lights for decoration.
2 pieces of transparent acrylic box parts: easy to assemble and provides full access to your Raspberry Pi | High Quality Acrylic case with fan secures your model Raspberry Pi 3B/3B+/Raspberry Pi 4B;Fan Size:30x30x7mm | More easily access to the board, power, RCA Video, Audio, USB, LAN (model B only), SD card and Light pipes | Great heat dissipation performance.Comes with assembly screwdriver. | Package Includes:1x Acrylic Case with Cooling Fan, 1x Screwdriver, 3 x Heatsinks for Raspberry Pi 3B+/3B/2B, 4 x Heatsinks for Raspberry Pi 4B(Added on 2019.7.26)
Compatible with Raspberry Pi 5 --- This Armor Lite V5 Aluminum Heatsink is only designed for Raspberry Pi 5 4GB/8GB. | Support PWM Speed Control --- Different from ordinary fans, this cooling fan supports PWM speed regulation, which is perfectly compatible with Raspberry Pi OS. | Good Heat Dissipation Effect --- With 3510 ultra-quiet cooling fan and thermal pads, it can lower the temperature of Raspberry Pi Board quickly. | Lightweight and Easy to Install --- With screwdriver and 2pcs screws, it's easy to fix the heatsinks with Raspberry Pi Board. | Package Includes: 1 x Armor lite V5 for Raspberry Pi 5, 1 x Screw driver, 2 x Screws, 4 x Thermal Pads, 1 x User Manual;
Compatible with Raspberry Pi 4 Model B --- This Armor Lite Aluminum Heatsink is only designed for Raspberry Pi 4 Model B 1GB/2GB/4GB/8GB Version. | Support PWM Speed Control --- Different from ordinary fans, this cooling fan supports PWM speed regulation, which is perfectly compatible with Raspberry Pi OS. | Good Heat Dissipation Effect --- With 3510 ultra-quiet cooling fan and thermal pads, it can lower the temperature of Raspberry Pi Board quickly. | Lightweight and Easy to Install --- With screwdriver and 2pcs screws, it's easy to fix the heatsinks with Raspberry Pi Board. | Package Includes: 1 x Armor lite heatsink with pwm fan for Raspberry Pi 4B, 1 x Screw driver, 2 x Screws, 4 x Thermal Pads, 1 x User Manual; | For Raspberry Pi Aluminum Case with Heatsink Fan, please refer to ASIN B0BRBZQ882.
This is a retro game case made for Raspberry Pi 2B / 3B / 3B +; Case with Quick Charger 3.0, refer to ASIN B09R1LVW5R | It has a simple shape, retro design | Built-in fan can help raspberry Pi 2B/3B/3B+ cool down during you play games. | Easy to install;Retro appearance;Superb craftsmanship;Lightweight and compact | Pacakge Includes:1 x Nes3Pi (with fan inside);4 x Aluminum Heat sink;NOTE: Raspberry Pi is not include in the package!
This Game5Pi case is Only for Raspberry Pi 5 8GB/4GB. | With Armor Lite V5 Cooler, it can lower the temperature of Raspberry Pi Board quickly. | GeeekPi RPI 5 Case can accurately access usb-c power jack, micro HDMI ports, usb ports, Ethernet jack, sd card slot, power button, 4-lane MIPI DSI/CSI connectors and so on. | The case is made of very lightweight aluminum and can protect the Raspberry Pi 5 board very well. | Package Includes: 1x Case for Raspberry Pi , 1 x Armor lite V5 for Raspberry Pi 5, 1x Cooling Fan
The LCD has always been a device that acts as a window in human-computer interaction. For example, the prompt window on some instrument devices, the temperature and humidity prompt box, the device running status monitor, and the prompt screen of the counting device all have LCD figures. | The common LCD1602, LCD2004, and LCD12864 are fabricated using liquid crystal materials and communicated using the I2C bus. | It is a high-performance serial bus with bus rules and high-speed or low-speed device synchronization required for multi-master systems. The I2C bus has only two bidirectional signal lines, a serial data line (SDA) and a serial clock line (SCL). | Compatible with all devices with I2C interfaces, such as Arduino, raspberry pi, beagle bone black, tinker board, stm32, esp32 and more. | Package Includes:1 x LCD2004,1 x Jumpwire
Compatibility - GeeekPi Raspberry Pi 5 Case with Raspberry Pi 5 Active Cooler is designed for the latest Raspberry Pi 5 4GB/8GB Board.It supports X1000/X1001/X1003/N04/N05 PCIe Peripheral Board. | Raspberry Pi 5 Case - It can protect the Raspberry Pi 5 board from damage, dust and scratches. It can access all ports, including usb-c power jack, micro HDMI ports, usb ports, Ethernet jack, sd card slot, power button, 4-lane MIPI DSI/CSI connectors. | Raspberry Pi 5 Active Cooler - Raspberry Pi 5 Active Cooler combines an aluminium heatsink with a PWM fan to keep your Raspberry Pi 5 maintain optimal operating temperatures, ensuring reliable performance for various applications. | Package Includes - 1x Metal Case for Raspberry Pi 5, 1x Raspberry Pi 5 Active Cooler, 1x Screwdriver, 1x Screw Pack | NOTE - Raspberry Pi 5 Board is NOT Included! | For Pi 5 Case with Cooling Fan&Heatsinks, please refer to ASIN B0CJM52Y4H
GeeekPi Mini Tower Kit is designed for Raspberry Pi 5 8GB 4GB. | ABS Mini Tower Case is made of ABS material, with very high precision, and the 45-degree OLED screen display angle is more convenient to observe system information. The screen holder adopts a quick-release design, and the interior of the shell includes a design for arranging cables, which is convenient for arranging cables. | The interface adopts With a fool-proof design to avoid problems caused by wrong wiring, the installation is simpler and more convenient. | The screen driver board contains RGB three-color programmable LED ambient light, which can better render the light color according to your own needs. | The ice tower radiator included in the kit can not only provide good heat dissipation, but also increase the appearance. | Package Includes: 1 x ABS Mini Tower Case, 2 x Acrylic side panel,1 x 0.96 inch OLED Display(already mounted on the case ), 1 x ICE Tower Cooler, 1x GPIO Edge Extention,1x Assembly Manual (Note: Raspberry Pi 5 board is Not included in the package)
N04 M.2 NVMe to PCIe Adapter is designed for the latest Raspberry Pi 5. It supports the installation of NVMe (M-key) drives in M.2 format sizes 2230, 2242, 2260 and 2280. Extra custom CNC SSD mount screw, no soldering required. | For a Metal Case, please refer to ASIN B0CYNX2P9Z ; Metal Case with Cooling Fan ( ASIN B0CJM52Y4H ) ; Metal Case with Active Cooler ( ASIN: B0CMZ84GM8 ) ; Aluminum Case with Cooling Fan ( ASIN B0CLFYDT8Y ) ; Aluminum Case with Active Cooler ( ASIN B0CMZG2R73 ). | PCIe x1 interface in both Gen2 & Gen3 standards. The short trace routing of PCIe is more reliable and faster, fully meeting the signal requirements of PCIe 3.0. | Ventilation hole design provides excellent ventilation airflow for cooling. | Integrated voltage regulator delivering up to 3A for the 3.3V power rail, compliant with M.2 (NGFF) standard. | Comes with a FPC PCIe ribbon, M2 and M2.5 screws, spacers, and extra custom CNC SSD mount screw.
High-Speed NVMe SSD Support --- The HAT board supports M.2 NVMe SSDs for fast data access and storage. | M.2 Interface --- Utilizes the PCIe interface for high-performance communication between the SSD and Raspberry Pi. | Power over Ethernet (PoE+) Capability --- Streamlines the power supply setup by allowing the Raspberry Pi 5 to be powered through the Ethernet port. | 5.1V/4.5A Output --- Ensures that the Raspberry Pi 5 and any connected peripherals receive adequate power for optimal performance. | Pi 5 Active Cooler --- Raspberry Pi 5 Active Cooler combines an aluminium heatsink with a PWM fan to keep your Raspberry Pi 5 maintain optimal operating temperatures, ensuring reliable performance for various applications.
Includes Raspberry Pi 4 4GB Model B with 64-bit quad-core CPU (4GB RAM).For 2GB Version,please refer to ASIN: B0B7DFF7TY;8GB Version,please refer to ASIN:B09LYP7QH3 | This Raspberry Pi 4B case contains a super quite 40mm PWM fan and 4pcs heatsinks for good heat dissipation of Raspberry Pi 4B. | 5V 3.6A Type C Power Supply will make your Pi work more stable. With ON/OFF switch, it's convenient for you to power on and power off your Raspberry Pi 4. | 64GB High Speed Class 10 Card with Card Reader , can work with all version Raspberry Pi | Package Includes:1x Raspberry Pi 4B (4GB RAM); 1x Raspberry Pi 4B Case; 1x Cooling Fan; 4pcs*Aluminum Heatsinks; 1x 5V 3.6A Power Supply; 1x 64GB SD Card (with Card Reader) ; 2x 4K HDMI Cables
Includes Raspberry Pi 4 8GB Model B with 1.5GHz 64-bit quad-core CPU (8GB RAM), For 4GB version, please refer to ASIN: B0B3M2HKN6; For 2GB version, please refer to ASIN: B0B7DFF7TY; | This Raspberry Pi 4B case contains a super quite 40mm PWM fan and 4pcs heatsinks for good heat dissipation of Raspberry Pi 4B. | 5V 3.6A Type C Power Supply will make your Pi work more stable. With ON/OFF switch, it's convenient for you to power on and power off your Raspberry Pi 4. | Power supply with Professional Certification: TUV, RoHS Certification; Input: 100-240V AC~50/60Hz; Output: 5V 3.6A; Extended Cord:120cm | 64GB High Speed Class 10 Card with Card Reader, can work with all version Raspberry Pi | Package Includes:1x Raspberry Pi 4B (8GB RAM); 1x Raspberry Pi 4B Case; 1x Cooling Fan; 4pcs*Aluminum Heatsinks; 1x 5V 3.6A Power Supply; 1x 64GB SD Card (with Card Reader) ; 2x 4K HDMI Cables
Only For Raspberry Pi 4 Model B. | Support PWM Speed Control;With super quiet cooling fan (40x40x10mm) for heat dissipation of Raspberry Pi;Includes heatsinks for better heat dissipation | The power supply with TUV,RoHS Certification; It's real 5V 3.6A that can provide the Raspberry Pi board with enough power; | Package Includes: 1x ABS CASE, 1x 5V 3.6A US Plug Power Supply, 1x PWM Cooling Fan, 4x Heatsinks, 1x Screw Sets, 1x Screwdriver
Easy-to-install Raspberry Pi 4 case - The Raspberry Pi 4 case consists of three parts and there is no need to screw the case, just cover them tightly; It can be access to all ports of Raspberry Pi Board, such as GPIO port, HDMI port, USB port, Card slot. | Better Cooling System - Raspberry Pi 4 quite cooling fan 40x40x10cm and 4pcs aluminum heatsinks are good for heat dissipation of Raspberry Pi 4 Model B. This fan can be adjusted by PWM. The official Raspberry Pi OS supports the speed adjustment function. You can also control the speed of the fan by controlling the GPIO pin through a third-party program. | 18W 5V 3.6A Power Supply for Raspberry Pi 4 Model B - With ON/Off switch, it's convenient for you to power on and power off your Raspberry Pi 4; With Professional Certification: TUV, RoHS Certification; | 1m Micro HDMI cable for Raspberry Pi 4 Model B - High speed 4K HDMI cable 60P; 1m gold-plated micro HDMI to HDMI cable. | Package Includes: 1x Case for Raspberry Pi 4 Model B, 1x 5V 3.6A USB-C Power Supply, 1x 4010 Cooling fan, 1x Micro HDMI Cable (1m), 1x Micro HDMI to HDMI Adapter, 1x USB Card Reader, 1x 4pcs heatsinks, 1x Screw driver
This Nes4Pi case is Only for Raspberry Pi 4B;NES style; Lateral heat dissipation. | This Nes4Pi case can make your Raspberry Pi 4B become a NES retro gaming machine in one second! | Built-in 3510 fan can help raspberry Pi 4B cool down during you play games. | Package Includes: 1x Case for Raspberry Pi 4, 1x Cooling fan 35x35x10cm,1x 4pcs Heatsinks, 1x Screwdriver | Case with 2PCS Controllers, refer to ASIN B089LV4Q2R. Case with QC3.0 quick charger, refer to ASIN B09R1NFTYX
It's fit for Raspberry Pi 4B and Raspberry Pi 3B+; It's compatible with most of cases in the market; | Use CNC Machining manufacturing technology for Aluminum heatsink; With 2pcs little thermal tapes to attach to the CPU and LAN tightly for better dissipation; | The cooling fan updated to 3510 version and it will be more quiet and powerful for heat dissipation of Raspberry Pi Board; | Raspberry Pi Board Not Included! | Package Includes: 1x Cooling Kit( Aluminum Heatsink with Cooling Fan), 1x Think Copper Heatsink For Pi 3B+, 2x Thermal Tapes for Pi 3B+,2x Thermal Tapes for Pi 4B
Used for Raspberry Pi 4,Pi 3, Pi 2, Pi Model B+ & Retroflag NESPI CASE PLUS | The DC 5V cooling fan run smoothly and quietly and it's good for heat dissipation of Raspberry Pi. It can be assembled easily by screws. | The aluminum heatsinks has thermal conductive adhesive tape on the back. | Package Includes: 1x Cooling Fan, 1x Screw Set, 3x Heatsinks for raspberry pi 3B+/3B/2B/B+,4x Heatsinks for raspberry pi 4 Model B | NOTE: Raspberry Pi Not Included
Compatible with Pi4/Pi3B+/3B: USB-C power specially designed and tested for the Raspberry Pi 4; With a Type-C to Micro USB adapter for Raspberry Pi 3B+/3B | With Professional Certification: FCC, TUV, RoHS Certification; Input: 100-240V AC~50/60Hz; Output: 5V 3A; Extended Cord:120cm | With ON/Off Switch Design: With ON/Off switch, it's convenient for you to power on and power off your Raspberry Pi 4. | Multi-Protection Functions: Over voltage protection; Under voltage protection; Over temperature protection; Over current protection; Short circuit protection. | Package Includes: 1x 5V 3A US Plug Power Supply with ON/OFF Switch,1x Adapter for Raspberry pi 3B+/3B
Compatible with Raspberry Pi 4B/3B+/3B | It has passive heat dissipation due to without fan. | With 3pcs little thermal tape for better heat dissipation of Raspberry Pi Board | Female socket, double row, straight pin, 2x20 pins, Through Hole mounting.Pitch: 2.54mm/0.1" | Package Includes: 1 x Armor Case,3 x Thermal tape,1 x Allen wrench,4 x M2.5 Hexagon socket head screws,2x20Pin Female Header(Note:Raspberry Pi and Fan Not Included)
Wide Application --- The new 4-layers cluster case is designed for Raspberry Pi clusters | Simple Installation --- The long fixing screws are designed with flat head screws, smooth and easy to install. | Better Cooling Effect --- With 120mm 5V RGB LED Fan for better heat dissipation | Good compatibility with Raspberry Pi | Technology Support
Ice Tower Structure;Easy to setup; Raspberry Pi 4 Case with ICE Tower Fan: B07ZCX5KG6 | 5mm copper tube;Super heat dissipation | Rated power 0.4W @5V, 0.08A;DC 5V Power in (Can be powered by the Raspberry Pi) | Super Cool fan background light (Multicolor)
UPS Plus is a new generation of UPS power management module which supports OTA firmware upgrade and supports RTC onboard. | There are two INA219 chip onboard to detect batteries voltage and the voltage output from UPS Plus to Raspberry Pi. | Compatible with Raspberry Pi 4B/3B+/3B/2B/B+/B/A+/A | Package Inlcudes:1 x UPS Plus For Raspberry Pi,4 x M2.5 copper pillar,4 x M2.5 screws,4 x M2.5 long copper stick,4 x M2.5 nuts,1 x Acrylic shield,1 x Instruction
For Raspberry Pi 3B+/3B/2B | Safe Shutdown and Safe Reset;Functional LED power indicator | Functional POWER and RESET buttons | Easy access to the SD-Card and all other ports without opening the case | Package Includes:1x SUPERPi CASE-U (new),1x SD Card Case,1x Screw driver,1x Cooling Fan,1x 3pcs of Heatsinks,1x Flannel Bag,1x Manual
Horizontal Tower Design --- The horizontal layout of the cooler enhances heat dissipation by increasing the contact area with the ambient air, leading to more effective cooling. | Ultra-Thin Fins --- The fin array is designed to be ultra-thin, which maximizes the heat dissipation area and improves the overall thermal performance. | 4Pin JST Interface --- The cooler uses a 4Pin JST connector that is compatible with the Raspberry Pi's built-in fan control system, allowing for seamless integration and automatic speed regulation. | Automatic Temperature Control --- The cooler is designed to automatically adjust the fan speed in response to the CPU temperature, ensuring that the device operates within safe thermal limits. | Enhanced Cooling Efficiency --- The combination of the ultra-thin fin design and the automatic fan speed control mechanism results in superior cooling performance, keeping the Raspberry Pi 5 cool even under heavy workloads. | Quiet Operation --- With intelligent fan speed control, the cooler operates quietly, minimizing noise disturbance while maintaining high cooling efficiency.
USB dongle for Raspberry Pi Zero/Zero W/Zero 2/Zero W 2 helps you to create an easy access, portable PC with Raspberry Pi Zero/Zero W. Do not need soldering and wiring wire with the module to raspberry Pi. | It can make your Raspberry Pi Zero/Zero W/Zero 2/Zero W 2 as a PC stick, so that you can plug it to your computer and access Raspbian OS from SSH service or VNC service which installed on Raspberry Pi' TF card | It uses the test points underneath your Pi Zero to attach a full-sized USB connector. Convert your Pi Zero or Pi Zero W into a convenient USB dongle. | Just plug it into a free USB port and you can connect to your Pi over USB Ethernet and share your computer's internet connection without any additional cables or power supplies. | The USB interface can be inserted on the front or the back, without distinguishing between the front and the back. | If you use Zero 2/Zero W2,Please open up the "boot" partition and edit "config.txt", adding "dtoverlay=dwc2" to the bottom and save it
【Compatibility】NESPi 4 CASE specifically designed for Raspberry Pi 4 Model B (2GB, 4GB, or 8GB) | 【Safe Shutdown and Reset, Functional LED power indicator】It will be more safer when shutdown and reset (Scripts are necessary). The Pi 4B indicator is visible after installation. | 【SSD CASE(NOT including SSD)】This NESPi 4 Case comes with NES Cartridge style case for 2.5'' SSD, easy to install your SSD, enjoy an overall better computer experience! | 【Strong Heat Dissipation】30x30x7mm Cooling fan with customize aluminum alloy specially designed for Raspberry Pi 4 Model B to get better heat dissipation. | 【Access to All ports】NESPi 4 Case allows you to access to all ports of Pi 4B , and slots on the side of NESPi 4 CASE to allow more space for you to operate more freely;Easy to assemble.
Safe Shutdown and Safe Reset | Functional POWER and RESET buttons | PiStation Case+LCD specifically designed for Raspberry Pi 4 | Easy access to the SD Card and all other ports without opening the case | 4.3*800*400 Pixel LCD Screen with Stereo Speakers Buttons Screen aspect swappable. 4:3 to 16:9 | Package includes:1x Retroflag PiStation Case with 4.3 inch LCD Screen,1x Raspberry Pi 4 fan,4x Raspberry Pi Heatsinks,1x Flannel Bag,1x Instruction manual,1x Screwdriver