Detailed description: 1) DC type, water-proof sender 2) with clip on the back of the receiver. 3) Receiver with Led flashing light, be convenient for old and deafer man to identify the calling visitor. 4)any one music can be chosen among 16 moledies 5)one sender can control one or more receivers and one receiver can be controlled by one or more senders 6)remote control distance:30m-100m 7)transsimion frequence:433.92MHz 8)Sender:DC9V(6F22)/DC 12V 23A 9)Receiver:DC 3V(1.5V AAx2)