SDI SOLO C6 is canned Carbon Monoxide, designed to test CO detectors manufactured by System Sensor, Interlogix, and Honeywell. This is the equivalent of canned smoke that is used to test smoke detectors. It comes in a 10-ounce can and contains pressurized CO gas. In this form, SDI produced a safe, non-flammable way to truly test your CO detectors. This is the first UL classified CO detector tester which is impressive due to the general liability of CO gas.