GASCO Calibration Gas 116es-414-50 GASCO Calibration Gas 414-50 Mixture 300 PPM Carbon Monoxide, 40 PPM Hydrogen Sulfide, 1.45% Methane, (29% LEL), (58% LEL Pentane Equivalent), 15% Oxygen, Balance Nitrogen Contained in a 116 Liter Cylinder, For Use with Any and All Gas Detectors, Cylinder Connection C-10, Calibration Certificate NIST, Made in the USA