Engineered, double-laminate backing is extremely durable for the toughest applications. No more frayed edges and discs falling apart. The new ceramic grain self-sharpens thus cutting cooler and lasting longer than all other grinding discs. Quick, tool-free disc change to eliminate time wasted and increase production. Available in 2" and 3" discs for even the hard to reach jobs Speed-Lok TR discs allow for quick, tool-free disc change and increased production. They twist on and twist off and lock securely to the back-up pad. Norton SG Blaze self-sharpening design is ideal for high-pressure, heavy metal removal applications. 25 per package.