This is a very special idler. It uses a high speed double row bearing to handle abuse in the worst conditions. Use it between the supercharger and crank to prevent belt walking. Use it on the end of tensioners. It is light weight while still taking all the abuse you can throw at it. Hard black annodize 17 MM bearing bore Offset to one side for use as a replacement for VMP 58 MM, 75 MM, 90 MM, and 100 MM idlers with the single row bearing. Fits factory Shelby GT500 tensioners '07-14 7R3Z-6B209-AA '20+ KR3Z-6B209-A. Fits VMP upgraded Shelby GT500 tensioner VMP-SUT007. Fits VMP/Roush style tensioner VMP-SUT002 when used with VMP-ISPC-7-17-SM machined aluminum spacer. Fits VMP Odin/Gen3R upgrade tensioner for no-grind FEAD VMP-SUT009. May fit other tensioners from Thumprrr, Whipple, and Kenne Bell