[No batteries required] Press the button and kinetic energy is converted into electrical energy. No need to worry about battery replacement. [Distinguish front and rear doors] Press different buttons, and the receiver plays distinct melodies to indicate which door has a visitor. [Bright LED lights] Highly visible lights, suitable for users with hearing or vision impairments. [150-meter open-field range] Effective range under ideal conditions; actual range may vary depending on environment. [60 built-in melodies] A variety of chimes to enhance your home ambiance. [5 volume levels] Adjustable sound output to suit household needs — loud enough to hear, quiet enough not to disturb. [Easy pairing] Supports up to 8 buttons per receiver; no compatibility restrictions between buttons and receivers. [IP44 rated] Resistant to water splashes; for outdoor use, we recommend an additional waterproof cover. Specifications Receiver size: 95 x 65 mm Button size: 74 x 40 mm Input frequency: 50 / 60 Hz Volume range: 0–110 dB Melodies: 60 Note: 1. Range stated is for open-field conditions; walls and obstacles may reduce effective distance. 2. Operates at 433 MHz; not compatible with other brands’ doorbells or devices due to proprietary signal protocol. Product appearance, color, and labeling may vary slightly by batch without affecting functionality. Plug type: US standard plug — compatible with USA, Canada, Mexico, Philippines, Thailand, Taiwan, and India. Voltage: AC 110 V Color: Black Material: Plastic Package includes: 1 x push button 1 x receiver