RAE 600-0050-008 equivalent by GASCO 50 PPM CARBON MONOXIDE, 10 PPM HYDROGEN SULFIDE, 2.2 % METHANE (44 % LEL) , BALANCE AIR (20.9 % OXYGEN, BALANCE NITROGEN) CONTAINED IN A 34 LITER ALUMINUM CYLINDER, For Use with Any and All Gas Detectors, Cylinder Connection C-10, Calibration Certificate NIST, Made in the USA