Coolqiya Door Sensor White, 3 Receivers and 3 Door Sensors

Description With CE, FCC, RoHS certified. Long Range Transmission - up to 400 ft in open air.  Wireless Multiple Door Bells Chimes - Easy to expand door bells or chimes. You can expand additional 10+ door bells or ring chimes. 52 Different Ringtones and Four levels Volume to Adjust and they will keep the settings when power is removed, no need to reset. Strong Working Signal for most material door or wall, including glass, metal, wood and more. Usage: Door Entry Alert Chimes - Keep track of your little children; And use as door entry alert system for home /garage/office/retail store. Easy Installation How To Pair