Calgaz calibration gas 10PPM Hydrogen Sulfide (H2S), 50PPM Carbon Monoxide (CO), 2.5% (50% LEL) Methane (CH4), 20.9% Oxygen (O2) Balance Nitrogen 116 Liter Aluminum Returnable Cylinder, Inlet: C-10, Cylinder/Blend: 10ALR 10PPM H2S/50PPM CO/2.5%CH4/20.9%O2/N2, Catalog: A0891419