Wireless entrance alarm. Alerts you when someone, or something, enters or exits through the monitored zone. Compatible with all Heath Zenith wireless doorbell chimes and buttons. Includes a battery operated doorbell chime and battery operated door/window sensor. Doorbell chime requires (3)AA batteries, not included. Door/window sensor requires (1)CR2032, included. The chime can connect with up to 10 Heath Zenith wireless doorbells at a time. Features a transmission range of 150-feet, a strobe effect, adjustable volume up to 85dB, and 10 melodies to choose from. Includes 1 wall anchor and double-sided tape for mounting.