Universal Security Instruments 10 Year Tamper Proof Permanent Power Sealed Battery 2-in-1 Smoke and Fire Smart Alarm, Model MI3050SB 2-in-1 Smoke and Fire Smart Alarm provides 10 years of continuous protection against fast flaming and slow smoldering fires Lithium-free 10 Year Sealed battery never has to be changed Features microprocessor intelligence to virtually eliminate nuisance alarms Fast and easy to install, no wiring required Patented Quick Find Alarm Origination- Easily Locate the first alarm that sounded