GASCO Calibration Gas 900es-414-CO2 300 PPM Carbon Monoxide, 10 PPM Hydrogen Sulfide, 2.5% Carbon Dioxide, 1.45% Methane (29% LEL), (58% LEL Pentane Equivalent), 15% Oxygen, Balance Nitrogen Contained in a 900 Liter Factory refillable cylinder, For Use with Any and All Gas Detectors, Cylinder Connection CGA 330, Calibration Certificate NIST, Made in the USA