F105325PM59 equivalent by Gasco 100 PPM Carbon Monoxide, 2.5% (50% LEL) Methane, 25 PPM Hydrogen Sulfide, 18.0% Oxygen Balance Nitrogen 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