Product Information:About the BRK 7020B 120V Hardwired Photoelectric Smoke Alarm with Battery Backup and Escape LightThe BRK Electronics 7020B comes equipped with all the great features you would expect from an outstanding smoke detector. The BRK 7020B utilizes a photoelectric smoke sensing chamber that detects smoke particles quickly and accurately, reducing the amount of nuisance alarms. Also included in the BRK 7020B is a 85db horn, a silence / test button, an easy access battery compartment for quick battery changes, a bright escape light, and Red / Green LED indicators to let you know if your BRK 7020B Smoke Alarm is working properly, and is in alarm mode (or DC mode). The BRK 7020B uses OptiPath360 Technology which provides a 360 degree coverage area allowing coverage to the ceiling and walls. In addition to housing so many important features, the BRK 7020B is capable of being interconnected to up to 18 devices, 12 of which can be smoke alarms. Features:#149; Photoelectric smoke sensing technology#149; Single button test/silence#149; Escape light illuminates path to safety#149; 9V Battery Backup#149; Optipath 360 Technology: patented technology provides 360 degrees of direct access to the smoke sensor#149; Perfect Mount: allows for easy alignment of alarm#149; Dust Cover#149; Easy Installation/Maintenance Specifications:#149; Alarm Dimensions: 5.0 dia x 2.1H#149; Operating Voltage: 120V AC 60Hz w/ 9V battery backup#149; Operating Current: .045 amps (standby/alarm)#149; Temperature Range: 40deg; F (4deg; C) to 100deg; F (38deg; C)#149; Humidity Range: 10 to 90 relative humidity (RH)#149; Audio Alarm: 85dB at 10 feet#149; Test/Silence: Electronically simulates smoke condition, causing the unit to alarm#149; Alarm Reset: Automatic when smoke clears#149; Interconnections: Up to 18 units of First Alert or BRK Smoke, CO and Heat Alarms. Maximum of 12 smoke alarms.