Calibration Gas Gas Name Methane Air Gas Mixture 1 Percent Methane (20 Percent LEL) 20.9 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