
I had to cut shoe lasts with some tricky inside and outside corners. These protractors do exactly what they're supposed to do - you hold them up against a wall and straighten them out, then read the angle off a (correct) dial. Put that angle on the saw and you're done. The instructions are a bit sparse, but with a few YouTube videos and a little practice it works well. If I had done a larger project I might have invested in an aluminum or one with better metrics, but it was fine for my needs.