Johnson Level & Tool 1941-0700 7-Inch Johnny Square, Professional Aluminum Rafter Square ACCURACY AND DURABILITY: This aluminum rafter angle square boasts a solid aluminum body with CNC machined edges for greater accuracy and durability for any job or worksite BUILDERS AND CONTRACTORS: The thick edge is useful as a saw guide. It can be used directly with the saw against the square for cross cuts or angled cuts using the etched protractor scale. It can be used indirectly as well, using the scribing notches to create a saw cut line for rip cuts SIMPLIFY STAIR LAYOUT: The Johnny Squares integrated distance and angle scales let you quickly and accurately mark your cut lines on your stringers and, of course, this rafter square has scales for cutting hip, valley and jack rafters ONE NUMBER LAYOUT: For roofs, solar panel supports, stairs, cabinets trim work and many other layout projects. The rafter scales are laid out mathematically to avoid time consuming calculations ADDITIONAL FEATURES: Permanent graduations with easy-to-read numbers, continuous scribing notches  ideal for ripping at 3-1/2 and 5-1/2, 2x4 board dimension markers for measuring 1-1/2, 3 and 3-1/2, low-glare protective powder coated finish