260FT Range Doorbell Wireless Detector for Doors and Windows, 39 Ringtones, 1 Doorbell Alarm with 4 Pairs Door Sensors, Home Security Door Chime, Store Security, White

DOORBELL DETECTION KIT – This wireless alarm detector emits a volume of 110dB when the door or window is suddenly open. It is a good helper for children, home, garage, school and safety.
EXTENSIBLE SYSTEM – The doorbell detector kit can be extended up to 20 sensors and 20 receivers to fully cover your property and safety. Ideal as a door alarm for home security, but also as a door bell for shops at the entrance.
EASY INSTALLATION – Simply plug the alarm receiver into a power outlet and open the double-sided adhesive attached to the mini black door detector and attach it to the door or window. Attention: Do not install it on a metal door, which affects the signal of the door detector, and make sure the distance between two door detectors is less than 0.4 inches.
39 RINGTONES – The receiver has 39 melodies and 5 adjustable volume levels from 0 to 110 dB; the door alarm detector has a memory function, and the original adjustment will be maintained after power failure.
80M/260ft RANGE – Wireless door bell Wide range The wireless receiver can carry up to 250m. When someone opens the door or window or the pet comes home, you will be alerted by a ringtone.