The plug-in chime will be activated when a visitor is pressing the smart doorbell. Plug-in chime is a practical tool that matches with smart doorbell, and they both provide home security for you! Note: Size and color may be slightly different due to manual measurement and different light conditons or other reasons, please in kind prevail. Thanks for understanding. Specifications: Color: Black/ White (Optional) Material: Plastic Plug: US Voltage: AC 90~250V Frequency: 433MHz Power Consumption: 10mW Volume: adjustable, up to 110dB Music Selection: Support Chime Size (plug not included): 82 * 82 * 20mm / 3.2 * 3.2 * 0.8in Package Size: 9.5 * 9.5 * 7cm / 3.7 * 3.7 * 2.8in Package Weight: 100g / 3.5oz Package List: 1 * Plug-in Chime 1 * User Manual (English) 433MHz frequency, compatible with wireless video doorbell. Plug-in chime, easy to use, designed for indoor use only. Adjustable volume, low to mute, up to 110dB. Different melodies for selection, meeting various needs. A chime can pair with multiple doorbells, a doorbell can pair with multiple chimes.