GASCO 116r-421 | X05NI79CA162VF3 | Calibration Gas | Carbon Monoxide 100 PPM, Methane 50% LEL, Hydrogen Sulfide 25 PPM, Oxygen 18%, Balance Nitrogen in a 116 Liter Cylinder, For Use with Any and All Gas Detectors, Cylinder Connection C-10, Calibration Certificate NIST, Made in the USA