Calibration Gas Gas Name Hydrogen Air Gas Mixture 2 Percent Hydrogen (50 Percent LEL) Balance Air Background Gas Air Cylinder Capacity 66L Cylinder Material Aluminum Alloy For Use With Any and All OEM Gas Detectors Connection Size C-10 Max Pressure 1200 psi Cylinder Dia 2-9/10 In. Cylinder Height 10-1/2 In. Accuracy +/-5 Percent Calibration Certificate NIST