Complex sentence: Glock Ges.m.b.H., an Austrian firearms manufacturer, utilizes the Tenifer process to protect the barrels and slides of the pistols they manufacture, save the units manufactured in the US, where the Tenifer finish is not allowed due to chemical regulations that do not exist in Austria.
Split into simpler sentences: Glock Ges.m.b.H., an Austrian firearms manufacturer, utilizes the Tenifer process to protect the barrels and slides of the pistols they manufacture. Note that the Tenifer process is not used in the Glock pistols manufactured in the US, because that finish is not allowed due to chemical regulations that do not exist in Austria.