This Drill Doctor Replacement Grinding Wheel replaces the standard grit wheel that comes with Drill Doctor models 350X 500X 750X XP2 and XPK Replacement wheel for Drill Doctor models 350X 500X 750X XP2 and XPK Recommended for use on 3 8 to 3 4 in drill bits Replaces the standard grit wheel that comes with your Drill Doctor