Product Description The Big 12is seven tools in one: a framing square, try square, miter square, protractor, saw guide, stair gauge and out-of-square corner angle finder. Its constructed of heavy-gauge aluminum alloy and includes theLayout Barfor use in determining out-of-square corners. Also included are the SwansonBlue Book for roof and stairway layout and Layout Bar with hardware. From the Manufacturer Swanson's Speed Square is a popular pocket sized square that incorporates features of the framing square, tri, mitre, and protractor squares. Common rafter and hip/valley rafter scales permit one-number references for all cuts. The square is merely rotated to the proper roof pitch value on either scale to assure the correct angle cut. The slot along the scales will accommodate an adjustable locking pin for repetitive cuts using any 1/4-inch bolt and nut. Comes with a handy, 62 page pocket sized booklet that provides vital instructions, reference diagrams, and tables for the construction of roofs and stairs. Heavy gauge aluminum alloy with matte finish to prevent glare 1/4 in. and 1/2 in. spaced notches to facilitate scribing lines Black gradations for easy reading Patented layout bar Great for deck framing and stairway building!