20pcs 5mm 940nm LEDs Infrared Emitter and IR Receiver Diode for 5MM Infrared 10 Emission + 10Receiver Tube (Pack of 10Pairs)

They do what there supposed to do

These arrived quickly, I've only used the transmitter diodes so far. There is a total lack of data beyond that the Tx diodes are the clear ones, the dark ones are the receivers (the dark plastic blocks out visible light and only lets the invisible Infra Red rays in).You can't see the light from the Tx, an IR camera will show it. The long lead is +ve, they start to conduct at 1.3V, max safe current is probably about 100mA, a series resistor is essential, say 22 ohm from a 3v3 signal, 39 ohm from 5v. Hope that helps!