Solid aluminum body with CNC (Computer Numerical Control) machined edges for greater accuracy and durability. Low-glare, protective powder coated finish. Permanent graduations and numbers are easy to read. Thick edge is useful as a saw guide. Scribe notches starting at 1-3/4 In. transfer outside increments from pivot point. 12 In. spans wider boards, simplifying layout and measurements. Complete instruction manual included with rafter tables.