SGF GAU01-012 - OEM German Made Flex Coupler - Bolt Circle 110mm/Bolt Hole 12mm/Bolt Hole Length 38.50mm SGF flex couplers have the part number formed into the flex coupler itself. By comparing the number on your flex coupler with the SGF part number, you insure the correct fit every time The SGF flex coupler is the same flex coupler you purchase from BMW, Mercedes, Cadillac or other OEM manufacturers SGF has manufactured over 90% of OEM flex couplers since 1946 Many aftermarket couplers do not contain the internal fiber wrapping that characterize genuine SGF couplers. This internal wrapping determines strength, stiffness and the torsional requirements your vehicle requires With drive shafts rotating in excess of 3,000 RPMs, do not risk installing a low quality flex coupler in any of your vehicles.