... to use and install 2.good quality with competitive price 3.used for family 4.Special price Special pricemain features:1. Dial up ... sudden alarm to prevent people from destroy. 7.Can work with the wireless P.I.R sensor, wireless smoke detector, break ... so on. 8.Easy to use, with the competitive price, every family can have it.9.with back up battery, work 24 hours ...