Edwards Signaling 517TCSB Series Photoelectric Single Station Smoke Alarms are designed to give reliable early warning of the presence of smoke where both audible and visual alarms are required. The series features a 90 dB solid state piezo signal and a 177 Candela strobe with "FIRE" lettering. Kidde 517TCSB Series provides the 3 pulse temporal pattern evacuation tone as a standard feature. The smoke alarm operates on the light scattering principle, a superior method of detection utilizing a pulsing LED light source and a photodiode sensor in a fully screened sensing chamber. Upon activation, the alarm will emit a 90 dBA local audible signal and activate the high intensity strobe. During the alarm period the strobe will flash at a brightness of 177 Candela 60 times per minute. Designed for ceiling or wall moutning on a 4" (102 mm) square mounting box using a universal moutning plate. Quick-disconnect plug connection. The Edwards 517TCSB Series Photoelectric Smoke Alarms are designed for use where both audible and visual alarms are required.