Pinnacle 4" Double Square

I use this in my wood shop and I use it all the time. It is very handy for most chores on the bench and for squaring up saw blades.

I bought one of these from my local Woodcraft store. Apparently there was a burr under the thumbscrew. It was VERY difficult to loosen the thumbscrew once it was tightened. I disassembled the square and attempted to remove the burr, but I was unsuccessful. It seemed smooth under the thumbscrew, but still took a tremendous effort to loosen the thumbscrew. I returned the square to Woodcraft and bought the more expensive Starrett double square. Problem solved.