Carbon Monoxide Alarm, Battery Chemistry Alkaline, Battery Location Back, Battery Locking Pin No, Battery Size Not Applicable, Detector Type CO Detector, Features Compact Plug-In Design Covers Only One Outlet. Large, Bright Display Screen. Peak Memory Recall. 7 Year Product End-of-Service Warning. Meets UL, NFPA, FHA, and HUD Standards, Includes Plug-in Design Cover, Power Source Hardwired, Sensor Type Metal Oxide, Semiconductor, Visual Alert Type Digital Display, LED, Volume Level 85 dB @ 10 ft