Norton is one of the top manufacturers of Grinding Wheels and Abrasives in the world. A Quality product.
6" x 3/8" x 1/2" arbor hole. 39C is a Green Silicone Carbide or Crystolon Abrasive used mostly on Carbides. This is 100 grit which is a Fine wheel. The H hardness indicates a softer grade. Great wheel for grinding harder carbides, Knife blades, etc.