Kidde SL177i Fyrnetics Hardwire Strobe Light for the Hearing Impaired, Interconnectable Provides a bright visual signal to warn of a smoke heat or CO hazard Benefits the hearing impaired allowing a visual alert of a danger Includes a tamper resist pin that helps to deter theft and tampering Quick connect power harness makes installation fast and easy. Make certain all devices are wired to a single, continuous (non-switched) power line, which is not protected by a ground fault interrupter. A maximum of 1000 ft. of wire can be used in the interconnect system Kiddes strobe lights meet the requirements of Underwriters Laboratories (UL), an independent facility that tests products for compliance with widely-accepted safety standards