Choose the screen-bak durite Q421 medium grit screen cut sheet for scale, rust and corrosion removal with minimal loading. This reusable, waterproof die-cut sheet features a P-graded silicon carbide abrasive for outstanding cutting power. A more effective option for use on light to moderate applications than paper or cloth cut sheets, the Q421 can be used with a sanding block or board on hard and soft woods, fiberglass composites and a variety of metals or for hand sanding projects in home or commercial settings.