Draeger 4594639 equivalent by GASCO Calibration Gas, 100 PPM Carbon Monoxide, Methane 2.5% (50% LEL), 25 PPM H2S, 17% Oxygen, Balance Nitrogen contained in a 34 Liter Disposable Aluminum Cylinder, For Use with Any and All Gas Detectors, Cylinder Connection C-10, Calibration Certificate NIST, Made in the USA