The Most Popular/Useful Shapes & Sizes
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.
Big Book Catalog, Issue:66, Page:467