Rodann Electronics CXRX1000A Wireless Magnetic Indoor Transmitter and Receiver up to 500 ft. Magnetic detector powered by CR2450 coin cell 3VDC battery &#40;included&#41; Indoor Wireless transmitter up to 500 ft Long battery life circuit design Fully automatic&#44; no alignment required. Receiver powered by economical 12 Volt DC&#44; UL Approved&#44; plug-in &#40;no batteries to change&#41;.