This rechargeable, portable Carbon Monoxide (CO) Gas Detector is rugged, easy to use and has both visual and audible alarms that notify the user when CO levels exceed specified limits. The internal sampling pump provides active sampling of gas which provides faster response times. It can be calibrated by the user based on the type of environment being tested. It includes a power supply to recharge the detector, as well as a sample tube that can be used to test the detector against a standard reference gas. It also comes in a hard, protective metal case with a cushioned, molded foam interior for device safety, storage and portability.