54-9045E Biosystems Calibration Gas Mixture Equivalent by GASCO 1.62% vol. Methane, 50% LEL Propane, (50% LEL Propane Equivalent), 50 PPM Carbon Monoxide, 18% Oxygen, Balance Nitrogen, contained in a 34 Liter Disposable Steel Cylinder, For Use with Any and All Gas Detectors, Cylinder Connection CGA 600, Calibration Certificate NIST, Made in the USA