Bulk Packaged 20pc 1 1/4 inch Reinforced Cut-off Wheels. The grit in these wheels is black, so it is probably Silicon Carbide. Use with 1/16 inch Screw Mandrel which is not included. Compare to Dremel 426. A sampling showed thicknesses ranging from about 0.036 to 0.046 inches, but may vary. These are identical to the referenced Dremel Product, but without the packaging. We removed these from Dremel Packaging. For use with Dremel Type Rotary Tools.