Replaces your CO alarms that are over 5 years old. No Bags. No Tags. Full 5-Year service life, longer than CO Sentinel CMD-4M alarms. CMD-4M and CMD-3M that have reached end of life. Features Conforms to ansi ul std 2034 - marine Meets abyc a-24. nmma listed component Most reliable Boats dc electrical system or marine grade batteries supply power to the alarm No missing or dead batteries to replace Proven sensing technology Prevents nuisance alarms which could lead to confusion and disconnected detectors Advanced technology Alarm mute button with advanced technology that silences alarm while boat is ventilated Rapid recovery sensor resets when silenced or reactivates alarm if dangerous levels of co remain Loud. 85 db alarm alerts you to co danger Specifications Case Size: 3. 5" H x 2. 5" W x 1.