Calibration Gas Gas Name Carbon Monoxide/Hydrogen Sulfide/Methane/Air Gas Mixture 250 ppm Carbon Monoxide 40 ppm Hydrogen Sulfide 2.5 Percent Methane (50 Percent LEL) Balance Air Background Gas Air Cylinder Capacity 58L Cylinder Material Aluminum For Use With Any and All OEM Gas Detectors Connection Size C-10 Max Pressure 1000 psi Cylinder Dia 2-29/32 In. Cylinder Height 10 In. Accuracy +/-5 Percent Calibration Certificate NIST