[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 is being used. [Brilliant lights] Bright visual alerts, suitable for users with hearing impairments or low vision. [150-meter open-field range] Effective operating distance in open areas; actual indoor range may vary depending on walls and obstacles. [60 melodies] A selection of 60 chimes for personalized alert options. [5 volume levels] Adjustable sound output to suit household needs — loud enough to hear, quiet enough not to disturb. [Free pairing] One receiver can pair with up to 8 buttons; no receiver limitations. [IP44 rated] Resistant to water splashes; for outdoor use, a dedicated waterproof cover is recommended. 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, furniture, and other obstructions will reduce effective range. 2. Operates at 433 MHz; not compatible with other brands’ doorbells or devices due to proprietary signal protocol. 3. Minor variations in appearance, color, or labeling may occur between production batches — functionality remains unaffected. Plug type: US plug (compatible with Canada, India, Mexico, Thailand, Taiwan, USA, Philippines, etc.) Voltage: AC 110 V Color: Black Material: Plastic Package includes: 1 x push button 1 x receiver