GASCO equivalent for Portagas 90099056 Calibration Gas Mixture: 10 PPM Hydrogen Sulfide, 50 PPM Carbon Monoxide, 50% LEL Methane (2.5% vol), 18% Oxygen, Nitrogen Balance, contained in a 34 Liter Aluminum Cylinder, For Use with Any and All Gas Detectors, Cylinder connection C-10 5/8"-18 UNF, Calibration Certificate NIST, Made in the USA