GASCO 105ES-BTEX Calibration Gas 1 PPM Benzene, 10 PPM Toluene, 10 PPM Ethylbenzene, 20 PPM m-Xylene, 20 PPM o-Xylene, Balance Air contained in a 105 Liter ecosmart Aluminum Cylinder, Cylinder Connection C-10, Calibration Certificate NIST, Made in the USA