The byron smartwares by102 wireless plug in door chime has a 60 metre operating distance it has a choice of four melodies it features self learning codes that will keep the code even when the batteries run out and are replaced this plug in chime can have up to 2 bell pushes controlling the chime it has a 80 85d b rating depending on the sound compatible with all byron b ranges please note upvc metal doorframes may reduce the operating distance the plug in chime is mains powered the push requir