Sinvitron wireless doorbell with 1 Remote Button and 2 Plugin Receivers Operating at over 500-feet Range with 36 Chimes, No Batteries Required for Receivers 1 transmitter button triggers(rings) 2 chimes units; Romote transmitter button is rated IP44 Waterproof and acceptable for outdoor installation; FCC, CE, and RoHS certified. Over 500 feet (1000feet in the open area) working range, great for your apartment as well as your commercial space, also practical to care for the elderly or immobile patients as a paging alert device 36 different ring tones; Four levels of adjustable volume level; Soft sound to Loud sound depending on your preference. Easy Installation without wiring. Just plug receiver into an electrical outlet Mount transmitter through double-sided adhesive tape or included screws / anchors. Package contents:Doorbell Chime x 2,Button x 1,Battery 12V 23A x 1,Screws x 2,Double-side sticker x 1,User Manual x 1