The Husky 7.5 in. Aluminum Universal Square is a wall partitioning layout tool designed to save layout time for carpenters. It aids both professionals and do-it-yourselfers in laying out wall studs (both middle partition and corners), squaring windows and doors and scribing angles, rafters and seat notches. Also ideal for use as a saw guide, the square conveniently holds a chalk line and tape measure to help you work efficiently.