Wireless door sensor: transmission distance up to 120m in the open space and does not interfere with other equipment in your home. 5 modes available: the receiver has of 5 modes, welcome / doorbell mode (36 melodies available) / alarm / colorful light / night light, can adapt to different situations and meet different needs. Easy to install and install: no necessary cables or screws. The double-sided tape can hold the contact sensor firmly on the door or window. It is a timely gentle reminder when family, the elderly, children, visitors, visitors pets come in or out when someone enters the office or opens the mailbox. It is a doorbell used in shops, stores and restaurants to welcome customers; it also works as a security alarm to alert you and deter intruders SF20R Receiver 1)Material:durable ABS shell 2) Color : White 3) Receiver Volume: Welcome Sound 95dB, Alarm Sound 113dB 4) Power Supply: Receiver 3 AA Alkaline Batteries/5.0V USB Power Adapter . 5) The battery of the receiver can be used for 5-7 months (calculated by ringing 30 times a day) 6) Transmission and reception frequency: 433 MHz (less interference than 315 MHz) 7) Working environment temperature: Receiver: -10 ~+60 8) Working environment humidity: < 80% 9) Storage temperature: -20C~+70C WLS07 Door Sensor 1)Material: New ABS shell, durable 2) Power supply: 1 AA alkaline battery 3) Standby time: approx. 2 years 4) Standby current: