What is an Infrared Emitter? An infrared emitter, or IR emitter, is a source of light energy in the infrared spectrum. It is a light emitting diode (LED) that is used in order to transmit infrared signals from a remote control. If you're interested in home automation, these IR receivers and transmitter will solve a lot of your problems working with arduino, raspberry pi, etc.You could use these guys to build universal remotes that control all the devices in your home too!Features Including LED IR emitter and receiver Widely used in remote control and other remote devices Nice and simple to use, downloaded the IR remote library for arduino and with a simple sketch had this up and runningThe Dimention of the IR Emitter: Working Voltage:2.7~5.5V Forward Voltage: 1.2-1.5V Forward Current: 100mA Power: 100mW Frenqence:38KHz Receiver Angle:±45° Lens Color : Water Clear Operate Distance:18~20m Pin length: Approx. 25mm / 0.98" Total Length approx. 30mm Peak wavelength (nm): 940nm Operating temperature : -25~ +70 ?The Dimention of the 3 legs IR Receiver Model : VS1838B Working Voltage : 2.7~5.5V Low/High Level Voltage : 0.4V/4.5V Receiver Distance : 18M Frequence : 38KHz Receiver Angle : ±45° Bulb Size diameter : 5mm / 0.2" Pin Length : 22.5mm / 0.88" Epoxy resin package plus external shielding anti-dry design Anti-dry ability, able to withstand the environment dry scratch Output match TTL, CMOS level, active low Application:audio-visual equipment (speakers, TV, DVD, satellite receivers, etc.); household appliances (air conditioning, electric fans, lighting, etc.); and other infrared remote control products.Package Includes 5 Pair Infrared LED Diodes