Review on Flap Discs PCS 4 5 Inch by Bashar Shaffer

How well can you tell the difference between a 40's disc and a 60's disc? Seems pretty easy until they're all benched and none of them are marked. It's easy to distinguish 40 or 60 from 120, but the boundaries are erased fairly quickly. It would have been very easy to just stick a label with the grit on the back, but the manufacturer couldn't do that. Otherwise they work great.