BIG 12® SPEED® SQUARE W/LAYOUT BAR?, BLUE BOOK The Big 12® Speed® Square is a 12-inch version of the Swanson® Speed® Square with added features for building stairs. This innovative tool combines 7 tools into 1: 1. Try Square, 2. Miter Square, 3. Saw Guide, 4. Line Scriber, 5. Protractor, 6. Out-of-Square Corner Angle Finder, & 7. Stair Layout Square. The Big 12® Speed® Square is die-cast for durability and accuracy. Made of heavy-gauge aerospace aluminum alloy, it is built to last. Black-filled gradations stand out against a matte finish for easy reading and are simple to use with the Swanson® One-Number® Method of rafter layout. This model includes the Swanson® Blue Book for Roof and Stairway Layout as well as the Layout Bar? for use in determining out-of-square corners when building stairways. The Swanson® Speed® Square is our most popular product and remains the most trusted square of its kind. Look for the Diamond® cutout for genuine Swanson® products.