m-e modern-electronics 41098 Wireless door bell Complete set

You can either connect the transmitter economically to a 230 V mains socket and save space, or use it as a mobile handheld device. The power supply is supplied via built-in akku pack, which is charged in stationary operation at the socket. The mains plug can be simply folded into the casing to stop it from getting in the way. The wireless sender can be attached to the present bell system.

Price: 61.99 from Conrad Electronic