LEDMO Wireless Doorbell with 1 Remote Button and Plugin Receivers Operated at Over 900-Feet Range with Over 50 Chimes, No Batteries Required for Receivers, White Wireless doorbell operating oevr 900 feet in open air.The battery (12V 23A ALK)for transmitter has been installed. Please pull out the insulating strip before using. Over 50+ different ring tones. Four levels of adjustable volume from 25db to 110db. Remote transmitter button is rated IP33 weatherproof and acceptable for outdoor use. Easily plug receiver into an electrical outlet (no batteries required for main receiver). CE, FCC, RoHS certified Screws and double-sided adhesive tapes included for easy installation of the transmitter Flashing Light Hint. The transmitter button will flash blue light to add additional alert. The receiver will flash white light to give them a friendly hint.