1、SAFE: It has a detection distance of up to 12m and can detect scenes up to 120 degrees, which can meet your house security needs. With the smart home security system, you can live and come in and out with peace of mind. 2、SMART HOME ALARM SYSTEM: Support for Tuya alarm security system, you can secure your home with complete control of your door alarm from your smartphone and get instant notification of alarms in your house or apartment. 3、CUSTOMIZATION: You can add additional door and window sensors, motion detectors, wireless doorbells and sos remotes for different rooms in your home security system. It supports expansion of up to 9 sensors and 10 remotes or keypads that can be added to a WiFi alarm station. 4、EASY SETUP: Easily set up your wireless home security system in less than 1 minute without tools. Using wireless connection will not damage the wall. The alarm main unit should always be connected to a DC outlet. 5、ADAPTABILITY: Suitable for ios operating system and for Android operating system. WIFI connection is available, only for 2.4GHz WiFi network, 5GHz WiFi network is not supported. Item Type: Door Open Bell Material: ABS Weight: Approx. 186g / 6.6oz Music: 38 Selectable Songs Volume: 4 Levels Adjustable (Including Mute Mode) Operating Current: <120mA Operating Temperature: -10-55℃ Sensor Battery: 3xAAA Batteries (Excluded) Detection Distance: <12m / 39.4ft Detection Angle: <120° Wireless Frequency: 433Mhz Transmitting Distance: <150m / 492.1ft (Open Area, No Interference) 1 x Door Open Bell 1 x Sensor 1 x Sensor Fixing Base 1 x Universal Bracket 2 x Screw 2 x Expansion Tube