To order GfG Instrumentation calibration gas, simply find your unit and click on the Add button for the gas next to the instrument you have.  If you cannot find your gas detector, please Contact Us and we'll select it for you. 

GfG 450 4 Gas Detector 

18% Oxygen, 50% LEL Methane, 200ppm Carbon Monoxide, 20ppm Hydrogen Sulfide, balance Nitrogen. 58L - $206.00