Gentex 7139CS-W Hard Wired Wall Mount T3 Smoke Alarm & Backup

The 7139 for wall mount is a photoelectric single station smoke alarm designed to give reliable early warning of the presence of smoke where both audible and visual alarms are required. This model is hard-wired so you would need an electrician to hook it up.
The smoke alarm operates on the light scattering principle, a superior method of detection in smoldering fires. It has a pulsing LED light source and a photodiode sensor in a fully screened sensing chamber. When smoke enters the chamber, the infrared beam is deflected onto the sensor. The LED rate increases to 8 times the normal pulse rate, and after the photodiode confirms the presence of smoke for 2 consecutive pulses, it will produce the signal necessary to trip the audible and strobe light alarms.
The 7139 series provides the temporal 3 (T3) evacuation tone as a standard feature. When testing, it may take up to 16 seconds longer to go in or out of alarm.

• 177 candela rating (very bright strobe light).
• Solid state 90dB horn (very loud).
• Full function test switch (easy for you to test that it is working).
• Flashes 60 times per minute.
• Meets state, federal, and ADA requirements.
• Mounting hardware for ceiling.
• Temporal 3 (T3) Evacuation sounding device.
• Tandem connection up to 6 detectors per system.
• 9V battery backup (audible alarm only).
• Item Weight - 2 lbs.