The byron smartwares b305 wireless plug in chime has a 50 metre operating distance it provides a choice of two melodies and has volume control it features self learning codes and 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 the plug in chime is mains powered the push requires 1 x 23a battery included