This aluminum t-square comes in 30" length, and is great for lining up films when burning screens. When screen printing multi-color images, its essential to have all your color layers burned into the same spot on each screen for easy registration. This is where the t-square comes into play. Place the plastic edge of the t-square flush against the screen, and then place the film to where the registration marks line up with the aluminum edge of the t-square. This will make it very easy for you to burn each film into the same spot on each screen!. 1½" tempered aluminum shaft. Calibrated in inches and centimeters. ABS plastic heads is lightweight and nearly unbreakable.