Excellent review! On the 6" wheels. The 7A is hard, you can deburr a steel file with it. Literally. I used an old file to true the wheel per 3M instructions and was very surprised at how much material it removed. It removes saw marks, and makes a radius of a corner very nicely. The softer wheel was for 90% of my 7 build. Not only used for edges, but can highly polish a surface. I highly recommend purchase of both wheels. Mine have lasted 10 yrs.
