Billy:

It's a "Machinist's" or "Combination " square. The complete kit has an adjustable protractor, a 45 and 90 degree clamp, and the center finder.

Without the adjustable protractor they are available for realy low prices with equally low quality, but more than sufficient accuracy for anything you will need. Even find them in the 99 cent tool bins now and then.

A complete set, with an engraved scale and so forth runs close to $200 from Lufkin or Brown and Sharpe, a Starrett square would cost even more.

The Japs are making them in reasonable quality for lower prices, but even the Mitutoyo (best Jap preision tool maker) square doesn't have the feel and finish of a good Brown and Sharpe.

Bill.