GASCO | 34L-411 | X05NI80CA34E841 | 100 PPM Carbon Monoxide, 25 PPM Hydrogen Sulfide, 0.35 % Pentane (25 % LEL), 19 % Oxygen, Balance Nitrogen, Calibration Gas Mixture, 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