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Q: What's the difference between 80 grit and 60/90 grit, and what does it mean by ungraded?

A: 80 grit would just be a straight 80 mesh grit whereas 60/90 would be mesh sizes between 60 and 90. Both are used frequently for coarse grinding. Ungraded means that it's not all one grit size, it ranges between the two numbers listed.