First Alert CO400 Carbon Monoxide Detector, Battery Operated, 6-Pack , White This handy 6-pack of First Alert CO400 Carbon Monoxide Alarms utilizes electrochemical carbon monoxide sensors to monitor your space for carbon monoxide threats. The battery-powered design doesn't require an electrician; simply insert the included 9-volt battery into each alarm, and the carbon monoxide detectors are ready to go. The advanced electrochemical CO sensors detect carbon monoxide leaks from multiple sources, such as faulty fuel-burning appliances, blocked chimneys, and generators running inside or too close to homes. When CO levels become elevated, a loud 85-decibel alarm alerts you to the threat. Because CO evenly distributes itself, it's important to have a CO detector on every level and in every bedroom of your home. Designed to be simple to use, each CO detector has just one button that silences or tests the unit, as well as an end-of-life timer that lets you know when it's time to replace the device. Features Keep your family safe with this 6-Pack of easy to use, battery operated carbon monoxide alarms; battery powered alarms provide continuous monitoring of CO levels, even if there's a power failure Features an advanced electrochemical carbon monoxide sensor that accurately detects carbon monoxide levels, no matter where the detector is placed in the room A loud 85-decibel alarm sounds when CO levels reach dangerous levels To ensure complete protection make sure to place one on each level of your home and in each bedroom USA SHIPPING estimates delivery times and we work to get your item to you as quickly as possible and within those times, but please know it may take slightly longer than the estimate.