Norlab u105320pm1 Equivalent by GASCO CO 60 PPM, Methane 1.45%Vol = (58% LEL) Pentane simulant, H2S 20 PPM, O2 15%, Nitrogen Balance 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