Grinding Wheel -Professional Tool Mfg. Drill Doctor Standard Grinding Sharpening Wheel 180 Grit for Models 500X/750X 180 grit For drill bits 3/32" to 3/4" Fits models in 300, 400 500 and 750 range. Fits model DD350X - Ace no. 2152460 and model no. DD500X Ace no. 2161040