3 Styles: These grinding stone set bit includes 3 different styles, including flat round, column, and Spike shapes, classic aienna color, providing versatility for various projects. Easy Compatibility: Suitable for rotary tools with a 3mm shank, these sanding drill bits are easy to install and compatible with most rotary tool brands, providing convenience and flexibility in usage. Quantity and Size: With 60 pieces in total, you'll have an abundant supply of sanding drill bits to tackle multiple tasks, each style in different size, flat round is about 15mm in diameter, 42mm long, column is about 9mm in diameter, 43mm long, Spike is about 9.5mm in diameter, 43.5mm long. Durable Material: Made of high-quality aluminium oxide, these sanding drill bits are durable and resistant to wear, ensuring long-lasting performance and reliability. Efficient Polishing: Designed for polishing and deburring tasks, these drill bits are efficient in removing material and achieving a smooth finish on various surfaces, including metal, wood, and plastic.