Norton RazorStar AVOS fiber discs feature engineered shaped ceramic grain technology for the best cutting performance in the industry. This RazorStar AVOS F990S see-thru disc with speed-lok fastener is designed for medium to high pressure metal removal in the toughest grinding applications. The self-lubricating grinding aid treatment delivers a cool cut, and the patented hole design allows a view of the surface while reducing heat. A heavy fiber backing is strong and resists tearing, while the Speed-Lok arbor mount makes this disc simple to attach and remove without tools.