First Alert carbon monoxide detector, battery-powered Digital display stores, recalls and displays highest level of CO detected Test button Silence button for unwanted alarm and for low battery warning signal Front mounted Battery compartment for easy replacement LED for power, service & alarm Easy to install with 2 x AA batteries (included) Loud 85 decibel alarm Supplied with all fittings Product packaging may differ between clam shell and boxed Dimensions WxDxH: 180?50x220mm