door bells many sound selectable. wireless doorbell distance 50M, A.B.C.D.E digital code, normal doolbellwireless doorbell receiver 3pcs AA battery,transmitter1pcs DC12V battery OR 6 pcs AG-13 battery,remote distance 30M,A.B.C.D.E digital code,16 melody selectable OR ding-dong soundCE (EMC ), R& TTE, ROHS certification DOORBELL