Different Shapes More Efficient-Made into 10mm bullet shape, the grinding wheels for drill fit into tight spaces. Ideal for sanding after beveling holes in metal and wood. Made into 10mm and 15mm cylinder shape are ideal for smoothing, sharpening, deburring and other grinding and shaping needs. Sturdy and Durable - The hardness is similar to white corundum. The grinding stone for drill can be cleaned and restored after long-term use. They are stronger, sharper and more durable. Wide Compatibility-Use for sharpening lawn mower blades, screwdriver tips, knives, scissors, chisels and other cutting tools.Aluminum oxide sanding bits are commonly used in metalworking, such as grinding, cutting, and deburring steel, aluminum alloys, and other materials. They are also used for polishing and grinding the weld points of metal castings, rust removal, and sharpening screwdriver tips. WARM TIP - For your safty, please make sure you wear SAFETY equipment such as a face shield (or Full Coverage Goggles) and gloves. Keep a light touch, too much pressure can break the grinding stone What You Get Sanding Bits - You will get 14 Pcs 10mm bullet shape, 14 Pcs 10mm cylinder shape and 14 Pcs 15mm cylinder shape . Colour:As Shown Material:Alumina Package Contents: 42 Pieces Grinding bits