Check the listing for details. 10Pcs 8mm 5/16" Spherical Head Diamond Grinding Bits Round Ball Lapidary Tools. Color: Silver, Condition: New. Listed at 13.99 USD. JINGLING 10Pcs Diamond Coated 8mm 5/16" inch Spherical Head Mounted Points Grinding Bit with 3mm Shank Code 80F*3mm Specification: Product Name Diamond Mounted Point / Grinding Bits Tip Shape Round Ball Shape /Spherical Material Metal, Diamond Head Diameter 8mm ( Close to 5/16") Shank Diameter 3mm (Close to 1/8") Total Length 60mm ( 2-3/8") Grit 80 (Coarse) Color Silver Tone Package Content 10Pcs Description: Product Name: Spherical diamond grinding head, diamond ball, diamond carving bit Shank diameter 1/8" (3mm); Suitable for dremel, electric grinder, carving machine with a 1/8" collet Used for sculpturing, dressing, precision grinding and internal grinding carbide in ceramic, glass, precious stone, alloy and many other abrasive materials. Diamond grinding head is processes each kind of mold, hard alloy, glass apparatus, ideal correction tools such as jade carvings. Use with water as a lubricant is better Adding water when use the diamond grinding head is good, can improve the sharpness and the life We Can List Any Size & Amount of This Product: Head diameter from 1 mm to 40 mm We will send out your order within 1-2 days after payment has been received and cleared Please let us know if you are looking for other accessories or hardwareJust a friendly reminder: The Shank diameter of grinding bit is 3mm (1/8" inch)If your chuck of Dremel is 3mm (1/8 inch) or Universal 3-jaw chuck, then the grinding bit can be installed directlyHowever, it is NOT suitable for machines with 3/32 inch chuck, such as Electric Nail Drill