Made of premium Steel with high hardness, hard-wearing and anti-rust. Open mouth cup burr sizes: 008 009 010 012 014 016 018 020 021022 023 025 3/32 inch (2.35 mm) shank fits for electric rotary tool, drill, grinder, etc. Great for jewelry setting, lapidary making and much more. Name:Open mouth lapidary cup burr. Shank:All of the burr are 3/32inch round shank. Sizes:0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.1, 2.2, 2.3, 2.5mm. Easy to use:Can be used in hanging mills, bench mills,electric grinders, rotary tool, etc. Application:For carving and grinding of silver, jewelry, wood, walnut and more, recommended for olive core, beads, , wood, bone, precious soft metal, etc Colour:Silver Material:Metal Package Contents: 24 x Open Mouth Cup Burr Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.