MSA 10125695 Equivalent by GASCO, 60 PPM CO, 0.625% Methane, 15% O2, 20 PPM Hydrogen Sulfide, Balance 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