These are typical abrasive consumables. They fit 1/2" arbor bench grinders. The grit appears to be about right.Why 3 stars? Simple. The maximum speed is clearly rated as "3000RPM Max" on the packaging. Nothing about that in the ad on Amazon, though, unless you magnify the pictures. Maybe they've changed that since I got mine? Dunno.FWIW, I own three bench grinders. One is from the early 1960's, another from the mid 1980's and yet another is from the early 2000's. Two are U.S. made, one is imported. ALL run at 3600 RPM. This is very common bench grinder speed.In fact, it is my observation based on 50 years of working steel, including five years employed as a structural steel welder building heavy construction equipment that the average rotational speed of 120VAC supplied DIY style U.S. Bench Grinders is around 3,600 RPM. As I mentioned, I have checked my three, plus the various offerings from the box houses, HF, and so forth online. All common machines are between 3450 and 3600 RPM. To get a reliably sub-3000 RPM unit, would have to drop close to 300 dollar. This, to get a dedicated low speed or dual speed machine like a Rikon or JET. Nice tools, but not going to happen.For the average guy with his dad's old Craftsman bench grinder, these wheels aren't going to work. They are rated for a maximum of 3000RPM, which makes them suspect and probably dangerous to run at 3600 RPM.Too bad, I was ready to give them a five star rating. As it is, 3 stars and know your abrasive wheel max speeds. An exploding wheel is a very unpleasant experience.