Zero Air Oxygen O2 Calibration Gas or Cal Gas with a concentration of 20.9% balance Nitrogen contained in 34LS Aluminum Alloy Cylinder that is used for calibration and maintenance of gas detectors. Connection size C-10, Pressure 500 PSI, Cylinder 34LS Aluminum Alloy, Diameter 3.125 inches, Cylinder Height 10.64 inches, Weight 30.9 oz, Contents 1.2 cu. ft. Use with regulators 70,73-PBR,74-DAF,70-FMV,70/SS