Kidde i2010SCO Worry-Free Hardwired Lithium Battery Backup I12010SCO Smoke & Carbon Monoxide Alarm Provides Protection from Two Hazards - Fire and CO in one unit with 10-year sealed lithium battery backup. Sealed-In Lithium Battery Backup - No battery replacement required over the 10 year life of the alarm. Eliminates worry about removal or unauthorized deactivation of alarm. Voice Warning System - Verbally announces FIRE! or WARNING! CARBON MONOXIDE to help distinguish between threats. Audio Alarm: 85 dB at 10 feet Ionization Sensing Technology - Ideal for detecting fast flaming and other types of fires. Temperature Range : 40 degree F (4.4 degree C) to 100 degree F (37.8 degree C) Hush Feature - Temporarily silences nuisance alarms for approximately 9 minutes and will not allow hush mode unless the unit is in alarm mode.Interconnects - Up to 24 Kidde devices (of which 18 can be initiating)