The 180mm Metric Rafter Square has a stronger frame and is the most versatile rafter square. Scribe notches from 25mm-145mm allow you to easily and accurately rip lumber. A 25mm cutout in the rafter square helps prop pipe, making it easier to cut on the job site. A reinforced frame gives you more durability, while high visibility laser etched markings make the rafter angle square easier to read.