Edwards Signaling 517T Series Photoelectric Smoke Alarms are designed for multi-family, residential and institutional occupancies defined by NFPA 101, in compliance with UL 217 and NFPA 72. Available in several different configurations, the 517T series is engineered to virtually eliminate nuisance alarms and deliver outstanding performance wherever reliable fire protection is required. Edwards Kidde 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.