Altair Single-Gas Detectors monitor carbon monoxide, hydrogen sulfide, or oxygen for as long as 2 years on maintenance-free, no-change lithium battery (1,080 alarm minutes or 18 hrs. of service life). Triple alarm system has 2 LEDs, a piercing 95-dB. audible alarm, and a vibrating alarm. Stainless-steel button toxic gas sensors contain solid electrolyte to eliminate sensor leakage. Single-button gas bump checks are recorded and displayed onscreen as checkmarks for 24 hrs. to confirm sensor response. Automatically logs 25 latest alarm events. To read data or change alarm set points, connect unit to MSA infrared (IR) adapter via built-in IR communications port. Rubberized armorresists dust, , and radio frequency interference. Clips to helmet, belt, or clothing. Weighs 4 oz.