The VMP 90mm idler pulley uses a factory size and brand NSK bearing, when the proper sized bearing is used the need for double beairngs is eliminated. Use this idler to take up belt slack and get better wrap with smaller supercharger pulleys. Can be used with 2.6", 2.7" or 2.8" super charger pulleys on GT500.
Also used with Roush M90 and P51 TVS blowers when installing a smaller SC pulley. Will fit other applications that require a idler with 17mm bore.