CG-Q58-4JK BW Technologies Calibration Gas Mixture Equivalent by GASCO 1.25% Methane(50% LEL Pentane equiv.), 18% Oxygen, 25 PPM Hydrogen Sulfide, 100 PPM Carbon Monoxide Balance Nitrogen contained in a 58 Liter Disposable Aluminum Cylinder, For Use with Any and All Gas Detectors, Cylinder Connection C-10, Calibration Certificate NIST, Made in the USA