The infrared photo eyes are a People and Property safety device intended for use with automatic gate operating systems. Swing gate operators require at least one external monitored entrapment device for gate operation and Slide gate operators require at least two external monitored entrapment devices (one for each direction) for gate operation per UL325 the standard for gate operator safety. See gate operator installation manual. The transmitter can be powered by two 3.6 vdc lithium batteries (model - ER14505) or it may be hard-wired to the gate operator control board. The expected battery life should exceed 1 year. Rated range up to 42 feet / 13 meters in most conditions