Universal Security Instruments 10 Year Tamper Proof Permanent Power Sealed Battery Carbon Monoxide Smart Alarm, Model MC304SB Carbon Monoxide Smart Alarm provides 10 years of continuous protection against the silent killer - carbon monoxide Lithium-free 10 Year Sealed battery never has to be changed Smart Alarm Technology provides superior nuisance alarm resistance Table top or wall mount - versatile design makes it easy to place in any room of your room Maintenance-free for a decade of peace of mind