These are narrow circuit boards, each with 21 surface mount LEDs either red or green and with a PPM controller.
They operate on 5V DC just like a servo plugged into the RC receiver. A “Y” cable can connect two boards to one channel.
The PPM channel can switch the LEDs from: OFF to FLASHING to STEADY-ON.
They are ideal for multi-rotor arms or as night flying lEDs for planes.