585-790-041 IST-AIM Calibration Gas Equivalent by GASCO 35 PPM CO, 10 PPM H2S, 10% LEL Methane, 18% O2, Balance N2, 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