The D-22B is a two-button, two-channel hand-held digital radio transmitter. The transmitter can perform a variety of remote switching tasks when used with any of Linear’s Standard Digital “D” Series Receivers. Typically the D-22B is used in wireless or hybrid wireless/hardwire security systems. The transmitter is powered by a 9-volt battery. Pressing the right button will send a “Channel 1” signal, pressing the left button will send a “Channel 2” signal. Hold buttons for at least 2 seconds to activate the transmitter. The red LED on the face of the transmitter will glow as the unit transmits and the receiver with the matching digital code will activate.