GASCO Calibration Gas Equivalent for Portagas 10322035 10 PPM H2S, 35 PPM CO, 0.14% C5H12, 18% O2 in N2 contained in a 58 Liter Disposable Aluminum Cylinder, For Use with Any and All Gas Detectors, Cylinder Connection C-10, Calibration Certificate NIST, Made in the USA