The tool is machined from quality aluminum material then anodized for lasting protection. They have a one piece “Y” shaped body design with a 2-1/2° increment degree dial that turns 360°'s. The degree dial has a built-in dial for leveling the tool at various angles. The hardened center punch marks your set position by taping with a hammer (vial and center punch are replaceable for lasting service). Magnets in the legs will free up the users hands for a safer and more accurate layout mark. Use them to establish and mark a centerline at any angle around the circumference on a pipe or tank or as a protractor level.