The byron smartware db313 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 also comes with a portable chime that can be placed in a different room to the plug in chime it has a 80 85d b rating depending on the sound compatible with all byron db ranges the pl