General description 90 PCS Diamond Burrs are ideal for fine detail work, cutting, engraving, carving, retouching, and finishing on various materials including glass, metal, stone, ceramic, wood, and plastic. This set includes 30 different styles of burrs, making it versatile for all kinds of detailed work such as jewelry making, beach glass crafting, and stone cutting. Technical specifications Quantity: 90 pieces Shank diameter: 1/8 inch (3mm) Total length: 1.77 inch Material: Alloy Usage Wet drilling only; do not operate dry. Start the hole at an angle for better results. Gently move the drill bit along the sides of the hole while holding it in your hand. Allow the tool to do the work; avoid applying excessive pressure. Other information Package includes: 90 pieces in 3 boxes for easy storage and transport. These delicate diamond drill bits have a thin diamond coating and are not designed to withstand heavy abuse.