1、55 Bell Chimes Available: user can choose the tone as he like. 2、Simple Operation: comes with 2 transmitter and 1 receiver, easy to pair the transmitter and receiver. 3、Memory Function: the chime user set before won't change even the power is cut off. 4、300M Wireless working Distance: Stable signal transmission and good anti-interference performance. 5、IP55 Waterproof: built-in waterproof sealing ring can protect the elements inside against water and dust to prolong its service life. This pet door bell will solve the problem of your dog trying to open the door by scratching door. Just train the dog to learn how to use nose or paw touch the transmitter and the receiver will ring. Features: 55 Bell Chimes Available: user can choose the tone as he like. Simple Operation: comes with 2 transmitter and 1 receiver, easy to pair the transmitter and receiver. Memory Function: the chime user set before won't change even the power is cut off. 300M Wireless working Distance: Stable signal transmission and good anti-interference performance. IP55 Waterproof: built-in waterproof sealing ring can protect the elements inside against water and dust to prolong its service life. 5 Levels Sound Volume Adjustable: adjustable from 0-110dB, the mute mode can offers user with better usage experience. Touch Button: the interval between two bells is about 20 seconds, no need to keep pressing the button all the time. SOS Caller Function: With a hanging hole for being connected to neck strap or wrist strap, elder people can use it as a caller for help. Specification: Material: Plastic Color: Black Waterproof Grade: IP55 Working Temperature: -30℃ to +70℃ Working Distance: 300m (without barrier) Working Frequency: 433.92MHz Sound Volume: 0-110dB (5 levels adjustable, with mute mode) Certification: CE, ROHS, FCC, PSE, TELEC Transmitter Battery: 12V 23A alkaline zinc-manganese battery (built-in) Size: Receiver(length*width*thickness): 2.36*2.36*0.59inch Transmitter(diameter*thickness): 3.07*1.97inch Package list: 1 x Receiver 2 x Transmitter 2 x Adhesive Tape 1 x Manual 1 x Screwdriver