The Speed Square Swanson's Book of Rafter Lengths & Roof Construction is a comprehensive guide for carpenters and builders in the United States. It includes detailed instructions and measurements for constructing roofs using the Speed Square tool, specifically focusing on rafter lengths. The book serves as a valuable resource for professionals in the construction industry looking to accurately and efficiently calculate and cut rafters for various roof designs. The Speed Square tool, alongside the information provided in the book, ensures precise and reliable results in roof construction projects.