M&H Wireless Doorbell Home Door Chime Operating At Least 900ft/280m Range/1 Push Button (Transmitter)with Over 36 Chimes (White) 1)Adjustable volume and music, simple and convenient installation (the first default ding-dong ding-dong) 2)No electromagnetic radiation, pregnant women don't have to worry about. The service life of more than one hundred thousand times (click). 3)Remote control distance of up to 280M/900Feet,Use radio frequency transmitter technology,have ten million group coding,effectively avoid outside interference 4) The waterproof transmitter, not afraid of weathered. Anti interference design. 5)Simple and stylish appearancemade by new ABS material,no harm to the human body