CO Check is the convenient, dependable way to detect and measure dangerous carbon monoxide (CO)1 in both residential and commercial/industrial applications. The instrument combines superior accuracy and reliability with simple, one-hand operation. Intuitive "stoplight" LEDs and an audible alarm alert you to the danger level of CO present, while the large, easy-to-read LCD provides a precise readout of the exact CO level. A protective holster case with belt clip adds to your convenience. CO Check is a natural companion for our GAS-Mate Combustible Gas Leak Detector, since both enhance heating system safety. For accurate, reliable CO detection in a convenient, affordable package that has all the features you need, CO Check is the tool for you.