Cast zinc head with computer-machined gauging edges for greater accuracy. Acrylic yellow barrel vial. Hardened, removable scriber. Steel blade is permanently stamped in 1/8, 1/16, 1/32,and mm. For general carpentry use, combination squares have heads with fences at 45 and 90 degrees. The squares head slides along the blade and can be locked in position, allowing you to accurately transfer a distance and hold it while drawing your pencil line. Combination squares are good for marking lines on lumber that youll use for ripping, crosscutting, mitering, and making notches.