Large S-TN LCD high contrast. CO measurement with fast response time. High repeatability and high accuracy stand-alone device easy to carryout and operation. CO function with alarm setting. Large S-TN LCD high contrast easy readout. Data hold function for freezing the desired value on display. Data hold function for freezing the desired value on display. Microprocessor circuit assures maximum possible accuracy provides special functions and features. Auto shut off is available to save battery life. Power supply from batteries or DC 9V adapter in.