The Voltcraft CO-700 carbon monoxide detector is used to check the carbon monoxide levels in the environment. The device warns in two different ways: by displaying the carbon monoxide level on the LC display and through an audible alarm. The sound signal operates similarly to the clicking of a Geiger counter: the higher the CO concentration, the shorter the intervals between the sound signals. Above 200 PPM, a continuous sound signal is emitted, with further increases in CO concentration indicated by a rise in pitch. Thanks to its short warm-up time of just 2 seconds, the CO-700 is ready for use quickly.