GFV279 Honeywell Calibration Gas Mixture Equivalent by GASCO Sulfur Dioxide (SO2) 10 PPM, Carbon Monoxide (CO) 50 PPM, Methane (CH4) 50% LEL contained in a 34 Liter Disposable Aluminum Cylinder, For Use with Any and All Gas Detectors, Cylinder Connection C-10, Calibration Certificate NIST, Made in the USA