The STI Wireless Doorbell Button mounts near a door and when pressed triggers an alert through an STI wireless receiver (sold separately). The button mounts onto a wall with the included screws up 500 feet away from the receiver. Although intended for use as a doorbell the Doorbell Button also works as a panic button. FEATURES: Weatherproof for outdoor use. Supervised for low battery and signal reception. Compatible with any STI Wireless Alert Series Receiver. CONTENTS: Doorbell Button Coin Cell Battery (2) #6 Screws. NOTE: Requires an STI Wireless Alert Series Receiver to alert you.