GASCO 509 Calibration Gas 15 PPM Acetylene, 15 PPM Ethane, 15 PPM Ethylene, 15 PPM Methane, 15 PPM Propane, Balance Helium contained in a 900 Liter Factory refillable cylinder, For Use with Any and All Gas Detectors, TBD GAS Specific, Calibration Certificate NIST, Made in the USA