This Johnson 48 in. Aluminum Drywall T-Square is perfect for general carpentry use, such as marking cut lines on sheets of plywood, OSB, drywall and other board materials. Built to last from extruded aluminum with an anodized finish, it features screened, thermal-bonded 1/8 in. graduations in black that are easy to read. Solid, 4-rivet construction securely bonds the head to the blade.