This is a Ball V Stone by Foredom with a 3/8" head diameter, 3/8" head length, grit 80 (medium) and a 3/32" shank.
V Stones have vitrified, self-sharpening special aluminum oxide grain with a super hard porous bond. They are the coolest running and longest lasting abrasives. V Stones easily cut hard metals like titanium, chrome-cobalt, nickel-cobalt, tool steel, and stainless steel and softer metals such as lead, pewter, brass and aluminum with minimal smearing. They also work well on ceramic tile, porcelain, wood, acrylic, glass marble, granite, and agate. V Stones are also the newest type of abrasive for shaping, texturing, and detailing hard or soft wood carvings. They last 4-8 times loner than other abrasives and are a great improvement over standard aluminum oxide and silicon carbide mounted abrasives. V Stones cost much less per hour of use because or their faster cutting rates and much longer life. They are also an economical alternative to plated and sintered diamonds. 45,000 RPM Max Speed. Made in USA.