Take errors and guesswork out of your next drywall job with this 48 in Adjust-A-Square? from Johnson. The T-square's extruded aluminum blade and head are a robust 1/4 in T, creating a safer straight edge that prevents your utility knife from slipping, while its clear protective anodized finish will keep your tool safe from rust and corrosion. Its precision-machined head and blade lock together for a ideal 90 deg angle, making it ideal for most drywall work, but its head also adjusts to any angle for the unique angle cuts sometimes needed on the job. This T-square was also designed to be easy-to-use. It features thermal-bonded black 1/16 in graduations that are large and bold for easy reading and the T-square folds flat for easy transportation to and from your jobsite.