Diameter 6″. Center hole thread size: 5/16-24 EXT. 3M Xtract proprietary multi-hole pattern provides superior dust extraction to prevent loading, increase productivity, and provide a cleaner work environment. Low profile soft density beige foam provides flexibility to conform to a variety of complex surface geometries. 3M Hookit attachment system provides easy disc changes and optimizes disc life. Recommended for finishing applications using fine grade abrasives.