The Triplett GSM130 Portable Carbon Monoxide (CO) Meter with user-adjustable CO alarm level has a range of 0 to 999ppm and simultaneously displays current CO and max CO levels. The GSM130 can be used to check Carbon Monoxide (CO) levels in chimneys/flues, gas appliances (ovens, ranges, dryers), furnaces, internal combustion engines, portable generators, and all coal/wood/charcoal/oil/kerosene/propane/natural gas burning devices. The Triplett GSM130 features a 25ppm default alarm setting with user selectable settings of 30, 35, 40, 45, 50, 70, 100 and 200ppm. The Triplett GSM130 additional features include automatic calibration in clean air (0ppm) or use 100/500ppm standard gases, backlit dual LCD display, and auto power off. 1 year warranty.