This is the "Standard" jet we use in the Unimog carb and the Pinzgauer Carb for Sea Level to 4500' elevation. Extended usage above 4500' and you should go DOWN in jet size. The higher the altitude, the less O2, the less fuel required. Very common for truck running 140's to be in a "Rich" condition at high altitudes. Short term it doesn't cause a problem other than not running well. Extended periods, start dropping down in size. In the Tahoe area (Rubicon Trail) we will run 125 main jets. New Old Stock. No Longer Available from MB. Included in 0000715301RK - Complete Carb Rebuild Kit.