GASCO | 116L-421 | X05NI79CP160003 | 100 PPM Carbon Monoxide, 50% LEL Methane (2.5%), 25 PPM Hydrogen Sulfide, 18% Oxygen, in Nitrogen contained in a 116 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