BW CG-QT58-1 equivalent by GASCO 2.5% volume Methane (50% LEL), 18% Oxygen, 100 ppm Carbon Monoxide, 25 ppm Hydrogen Sulfide, 0.5% Carbon Dioxide, Balance Nitrogen Contained in a 58L Liter Disposable Aluminum Cylinder, For Use with Any and All Gas Detectors, Cylinder Connection C-10, Calibration Certificate NIST, Made in the USA