This universal transmitter is compatible with the Safeguard Supply "ERA" line of products. It may be used as a door/window contact or a wireless push button. When triggered, it will transmit a wireless signal up to 4,000 ft. to an ERA receiver - the ERA-DCRX or the ERA-RXPG. The transmitter is powered by a 3-volt lithium-ion battery which comes included with purchase. To purchase the complete kit, please see the ERA-UTDCR Warehouse & Business Wireless Doorbell Kit Designed for Business Use and the WDK-ERA-STROBE Warehouse Wireless Doorbell Kit / Entry Alert & Strobe Light For Large, Loud Areas.