The Big 12 Speed Square is a 12 in. 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, and 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. Look for the Diamond cutout for genuine Swanson products.