Smoke Alarm, Detection Method Ionization, Up to 24 Units Interconnection Capability, Power Source 120VAC, 9V, Audible Alert 85dB @ 10 ft., Horn, Visual Alert Red LED, Diameter 5-3/4 In., Height 1-1/4 In.Digital Readout No, Battery Backup Yes, Features Wireless, Hush Button Yes, Locking Pin Yes, Operating Temp. 40 to 100 Degrees F, Standards UL, NFPA, Federal Housing Authority, Housing and Urban Development and California State Fire Marshal GuidelinesManufacturers Warranty Length 10 Year Limited RestrictionsHazardous Material Smoke and Combination Smoke/CO AlarmsWirelessSmoke AlarmsTest/Reset button test11s alarm circuitry, alarm activation, and battery function. Several models include a hush button to silence nuisance alarms. 85dB horn. Easy installation. Operating temp.: 40 to 100 F. 120VAC, 60 Hz.Alarm Types: Ionization respond best to fast-raging fires. Photoelectric respond best to slow-smoldering fires. All interconnect units must interface directly with their own brand of interconnectable smoke and CO alarms.Expand your fire protection coverage with battery-operated unit 5MPL2. Replace 1 existing interconnected smoke alarm with AC-powered alarm 5MPL1. The AC-powered alarm bridges a home's current interconnected system so that when 1 alarm is triggered, all alarms will sound.Meet UL, NFPA, FHA, HUD, CSFM standards