The byron smartwares db303 wireless plug through door chime has a 30 metre operating distance it provides a single melody ding dong chime and operates using a fixed code its plug through feature means that there is no loss of socket another mains powered object can to be powered by plugging into the chimes socket it has a 80 85d b rating depending on the sound the chime is mains powered the push requires 1 x 23a battery included