GfG’s G450 is a compact and lightweight four-gas detector that continuously measures CO, H2S, O2 and combustibles in ambient air. Its functional and watertight design (IP 67) incorporates an impact-proof, rubberized housing to meet the toughest requirements of harsh environments. Interchangeable battery packs allow up to 25 hours of continuous operation. GfG Instrumentation,, (800) 959-0329. Circle 269