GASCO Precision Calibration Gas 900es-425X Mixture 10 PPM Hydrogen Sulfide, 0.14% Pentane (10 % LEL), 18 % Oxygen, Balance Nitrogen Contained in a 900 Liter Factory refillable cylinder, For Use with Any and All Gas Detectors, Cylinder Connection CGA TBD, Calibration Certificate NIST, Made in the USA