ZPE Griptec™ micro 3.25" Magnuson Products Jack-shaft Supercharger Rear set of 1:1 Pulleys. These Pulleys are designed to eliminate belt slip commonly found on Stock and High Horsepower applications. Often customers might result to rear cog systems, however they might not see much gain if any. This is due to the of the massive amount of heat the cogs and cog belt product. This heat transfers into the blower housing quite quickly and raises the Superchargers IAT's. The increased temperature reduces the quality of air entering the engine and lowers horse power. Using ZPE's Griptec™ micro in the rear of the Jack-shaft Supercharger you can lower belt tension while eliminating belt slip. This means lower temperatures being emitted from the rear belt system while allowing the Supercharger to make more of what you want... BOOST!!!