Standard Abrasives™ Quick Change TR A/O Unitized Wheels Soft/Medium density wheel blends surfaces to a nice finish. Increased edge durability over the 500 Series offers better and adds life for light deburring and blending applications. Aluminum oxide mineral is a good match for ferrous and non-ferrous metals, including aluminum. Open web is load , contributing to longer abrasive service life. Easy fastening and swapping of TR style quick change disc enhances tool efficiency and worker productivity Pack of 10