GASCO 509 Calibration Gas 15 PPM Acetylene, 15 PPM Ethane, 15 PPM Ethylene, 15 PPM Methane, 15 PPM Propane, Balance Helium contained in a 17 Liter Disposable Steel Cylinder, For Use with Any and All Gas Detectors, Cylinder Connection CGA 600, Calibration Certificate NIST, Made in the USA