AVANTEK Wireless Door Bell, CW-21 Mini Waterproof Wireless Doorbell Operating at
EASY TO SET UP: 2 transmitters included; can add more AVANTEK RB-1/CR-1 plug-in receivers for increased coverage; simply fix the transmitter on the wall without any wiring; includes 4 screws, 4 anchors, 1 key and 2 double-sided adhesive pads.