The Empire 2990 7 in. heavy duty rafter square features a solid aluminum extruded square that will Nt bend or break. Stamped conversion tables allow for quick and easy measurements. The thick edge makes for a safer saw guide and aluminum material will Nt rust or corrode. The 7 in. size allows for marking and cutting boards up to 7 in. wide. Graduated Ntches allows for smooth pulling of layout lines. The 2990 includes a helpful instruction manual with complete rafter tables.