The gentex 7139cs-w is a photoelectric smoke alarm designed for residential and commercial residential applications, including homes, apartments, hospitals, hotels/motels. The 7139cs-w is designed to give reliable early warning of the presence of smoke where both audible and visual alarms are required. The 7139cs-w is ANSI/UL 217 and ANSI/UL 1971 listed and is compliant with ibc/ifc standards as well as NFPA 72. . 120 vac with 9Vdc battery back-up . 90Dba temporal 3 evacuation piezo horn with a 3100Hz (nominal) horn frequency . Ada compliant 177 candela strobe (ANSI/UL 1971) . Wall mount . On-site washing program . Nominal 2. 5% sensitivity . 3 position test switch . Form c contact included . Tandem interconnect with all gentex tandem capable alarms . Low or missing battery indicator . Relays operate on battery back-up and will activate from tandem wire . Quick disconnect Wiring harness . Fully insect screened . 1 year warranty from date of purchase.