The Merit BPM-4 mandrel securely mounts bore polishers with a 1/2 -20 male thread onto a grinder that accepts a 1/4 -diameter shank. The one-piece mandrel design has a knurled portion for increased grip when installing and removing the polisher and is made of steel for strength and extended tool life. The mandrel has a threaded end that accepts the bore polisher, and it has a 1/4 -diameter shank that inserts into a grinder's chuck.Merit Abrasives manufactures abrasives for the deburring and finishing industries. Merit, founded in 1945 and headquartered in Cleveland, OH, meets International Organization for Standardization (ISO) standards 9000 and 14001. Mandrel mounts bore polishers with a 1/2 -20 male thread onto a grinder that accepts a 1/4 -diameter shank Knurled shank portion provides increased grip when installing and removing the polisher Steel provides strength and extended tool life UPC 088341541833 Model 08834154183 Brand Name Merit Unit Count 1 Count Part Number 08834154183 Manufacturer St. Gobain Abrasives Material Type Alloy Steel Item Dimensions 3 x 4.45 x 0.75 inches Number of Items 1 Construction Type Coated Grit Material Type Alloy Steel Additional Features Not_Performance_Used Compatible Material Steel Industry Standard Identifier BPM 4 Global Trade Identification Number 00088341541833