1750 or 3500, slow or fast, 6" or 8"... it doesn’t matter. Norton’s 3X grinding wheels are the fastest cutting, coolest wheels on the market. Norton’s patented SG grain gives the 3X’s an incredible burn free cut with controlled micro grain fracturing that constantly exposes fresh grain. This continuous refreshing of the surface helps speed up metal removal and keep your tools a lot cooler. Faster cutting and less burning also means longer wheel life. How much longer depends on you but from our experience - these may outlast your grinder. Two grits are available - 46 grit for heavy grinding such as establishing a new bevel and 80 grit for putting a working edge on your turning tools or primary edge on your plane blades. 6" wheels include bushing for use on 1/2", 5/8", 3/4" and 7/8" shafts. 8" wheels include bushing for use on 5/8", 3/4" and 7/8" shafts.