Part Number and name: G420-3 Blue Grit 1/4” grinding stones three-pack Used for/with: Abrasive wheel for use with Granberg motorized sharpeners and hedge trimmer attachments Fits: All Granberg 12-volt sharpening tools General description: Aluminum oxide based abrasive on a 1/8” threaded shaft. Use description: Use sharpening stones with Granberg grinders and hedge trimmer sharpeners