Besides just measuring 45° and 90° like a combination square, the Penta Square also measures 22.5° and 60°. But, that’s only four measurements; penta is a prefix for five. Either they’re considering 180° a measurement, or else they’re call it that because of the irregular pentagon-shaped body.
Kapro etches the 12″ stainless-steel blade in both Inch and Metric graduations. The bubble vial rotates within the body to check level and plumb in “all” positions. Absent is the thumb screw locking mechanism of a normal combination square. They’ve replaced it with their EasyLock mechanism, which they neglect to show in the literature.
Depending on where you look, the Penta Square could cost you as little as $6.
Penta Square [Kapro]
Penta Square [Woodworker's Supply]
Via Amazon [What’s This?]