Brownells "Premium Plus" stones are the very finest we can offer. Industrial grade cobalt is added to uniformly sized aluminum oxide crystals and bonded with special, cool-running adhesives to form the hardest, longest-wearing, fastest-cutting, grinding points available to the trade. Gives a smooth, ready-to-finish surface on all types of ferrous and non-ferrous metals. Stones resist filling and gouging; can be re-ground or re-shaped, lasting much longer than "hobby" grade points. Hardened steel shafts are nickel plated for long life and stay concentric even with repeated use. We picked our 10 most popular grinding points and put 3 of each into a convenient, easy- Mfg: Brownells SPECS: Shank - 1½" (3.8cm) long, 1/8" (3.2mm) diameter.