58L-404-17 100 PPM Carbon Monoxide 50% LEL Methane 25 PPM Hydrogen Sulfide 17% Oxygen in Nitrogen contained in a 58 Liter Aluminum Cylinder, Cylinder connection C-10 5/8"-18 UNF, Calibration Certificate NIST, Made in the USA | Alternate Part number X05NI80CP5856Q9