BESTEK Wireless Doorbell with 1 Transmitter and 2 Plug-in Receivers with 52 Chimes, 4-Level Volume, Nearly 1000-feet Range, No Batteries Required for Receivers (White) BESTEK Wireless Doorbell: 1 transmitter triggers 2 plug-in chime units over 500 feet (nearly 1000 feet in open area) operating range. Perfect for large house or big office use. 52 Ringtones with 4-level adjustable volume (Max.110dB). The 2 chime unit can be paired with different ringtones as you like. Plug-in receiver with 2-pin US plug is suitable for an electrical outlet easily, no batteries required. Remote control transmitter with IP33 waterproof case is ideal for outdoor use. Comes with double sided sticker, anchors, screws, and 1 * 12V 23A battery. Easy to install. Modern style, elegant in white, unique LED Blue light flashing in the dark. Low power consumption doorbell.