Calibration Gas Gas Name Hydrogen Sulfide Nitrogen Gas Mixture 2500 PPM Hydrogen Sulfide Balance Nitrogen Background Gas Nitrogen Cylinder Capacity 74L Cylinder Material Aluminum For Use With Any and All OEM Gas Detectors Connection Size C-10 (5/8 in UNF) Max Pressure 500 psi Cylinder Dia 4-1/4 In. Cylinder Height 14-1/4 In. Accuracy +/-5 Percent Calibration Certificate NIST