Calibration Gas Gas Name Hydrogen Sulfide Methane Oxygen Nitrogen Gas Mixture 15 PPM Hydrogen Sulfide 2.5 Percent Methane (50 Percent LEL) 18 Percent Oxygen Balance Nitrogen Background Gas Nitrogen Cylinder Capacity 58L Cylinder Material Aluminum For Use With Any and All OEM Gas Detectors Connection Size C-10 Max Pressure 500 psi Cylinder Dia 3-17/32 In. Cylinder Height 14-1/4 In. Accuracy +/-5 Percent Calibration Certificate NIST