Test 1A Lumidor Calibration Gas Equivalent By GASCO 50% LEL Methane, 50 PPM Carbon Monoxide, 25 PPM Hydrogen Sulfide, 18% O2, Balance Nitrogen contained in a 10 Liter Aluminum Cylinder, For Use with Any and All Gas Detectors, Cylinder connection Built in Aerosol Trigger, Calibration Certificate NIST, Made in the USA