Alphasense has introduced a two-gas, carbon monoxide(CO) and hydrogen sulphide (H2S)electrochemical sensor, measuring just 14.5mm diameter by 11.5mm deep. The D2 device ensures that the CO measurement is not influenced by the presence of H2S in either the atmosphere being monitored, or in multi-component calibration gas mixtures. The company is also able to supply single gas versions in its miniature 'D' family for chlorine and nitrogen dioxide detection.