They also sell expensive aluminum sanding beams. I could tape (2) 8" blocks to a piece of 2x4 and do the same thing. But I find the 8" blocks works fine. Many times only have sandpaper on 4" of the block and tape on the other end. Then I can spot sand high spots. The taped end of the block keeps it from tipping and causing waves in the sanding. I check the fret level often with a straight edge.