Carbon Monoxide and Gas Alarm Battery Chemistry Alkaline Battery Location Front Battery Locking Pin Yes Battery Size Not Applicable Detector Type Explosive Gas/CO Detector Features Patented Quick Find Alarm Origination Feature easily identifies the first alarm to sound in an interconnected system. Single Test/Silence Button. Easy Installation and Fewer Callbacks. Tamper Resistant Locking Pins for Alarm Battery. Meets UL NFPA FHA HUD and California State Fire Marshal Standards