CO110 CARBON MONOXIDE METER 0-1000PPM RANGE BEEP ABOVE 200 STANDARD CO-110CO110 carbon monoxide meter detects the presence of carbon monoxide (CO) and measures concentrations between 1 1000 parts per million (PPM). The meter indicates the presence of CO by a reading on the LCD and a beeper tone. The beeper function much like clicking of a Geiger counter: above 200 PPM, the beeper sounds continuously with the concentration of CO. From 35 PPM to 200 PPM, the beeper sounds discontinuously with the concentration of CO.