The byron smartwares by212 portable wireless plug in door chime kit has a 100 metre operating distance it has a choice of six melodies and offers volume control it features self learning codes that will keep the code even when the batteries run out and are replaced the battery powered portable chime can be taken anywhere within the operating range it has an 80 85d b rating depending on the chime selected compatible with all byron b ranges has a flashing light alert for the hard of hearing the pl