The Nighthawk, Digital Battery Operated Carbon Monoxide Alarm, Easy To Install Unit That Provides Reliable Protection Against The Dangers Of Carbon Monoxide, Digital Display Feature Adds An Advanced Level Of Protection Showing CO Levels In PPM Allowing You To See If Levels Change, Written Information & Instruction, Easy For Anyone To Understand, Small, Sleek Design That Is Suitable For All Living Areas & Has A 7 Year Limited Warranty.