1, ESP8266 ESP-01S serial WiFi wireless transceiver module used 4MB Flash, not 1MB flash. | 2, USB Programmer selectable working mode: On-board toggle switch. UART side for serial TTL debugging by AT commands, PROG for firmware programming. | 3, Programmer USB to serial TTL chip: CH340G, please check if your computer has installed the driver before use it. | 4, ESP-01 serial wifi module can be directly plugged into the yellow pin header of the USB programmer module without any connection wires. | 5, What you will get: 1pc ESP-01S 4MB wifi module + 1pc USB programmer ESP-01S adapter module. If you have any question, please feel free to contact us by clicking "WISHIOT" under the shopping cart(you can find Sold by WISHIOT under Buy Now button) and then clicking "Ask a question".