WARNING MSA GAS CYLINDERS ARE NOT COMPATIBLE WITH OTHER BRANDS OF GAS DETECTORS!!! Each MSA calibration gas is cylinder is shipped with an individual material safety data sheet (MSDS) and an individual copy of a certified of analysis. MSA certifies that the gas mixture in calibration gas cylinders was prepared gravimetrically, using NIST traceable weights. The lot number and nominal value of the constituents in percent by volume, percent by mass, PPM, or volume are specified on the cylinder. The uncertainty of the specified nominal value is also listed