Feature: 1. 38 Melodies And Adjustable Volume:The receiver has 38 ringtones for your choice. 3 adjustable volume levels, you can set voiced and silent (voiced: sound+indicator silent: indicator). 2. Support Long Distance Connection: Working range up to 230 feet (70 meters) between receiver and transmitter, and infrared detection range up to 3‑7 meters. 3. Function: Can be alerted to visitors, notice door opening, scare off unwanted intruders, or even know when your children have accessed restricted areas. 4. Easy Installation: The sensors can be installed or placed at any indoor position to provide you with a door entry alarm system. 5. Widely Use: Great for homes, offices, garages, yard, and shopping malls. Also can be used at the front door, back door, garage and driveway. Specification: Item Type: Motion Sensor Alarm Material: ABSApplication: Home, office, factory, shop security welcome and other places Battery: An infrared detector requires 3 x AAA batteries (without batteries) Voltage: 110 - 240V Infrared Detection Range: 3-7 meters Music: 38 music to choose, the side of the music button for adjustment Volume: three levels of volume adjustment (high, medium and low) side volume button for adjustment You can set voiced and silent (voiced: sound+indicator silent: indicator) Operating Frequency: 433MHZ Working Distance: 70 meters . Package List: 1 x Doorbell2 x Infrared Detectors4 x Bracket Accessories4 x Screw4 x Expansion Tube1 x Instructions