Depends on the types of quilts you make. For t short quilts, I use the 9 1/2 square and 12 1/2 square. Great for fussy cutting big blocks. For cutting almost everything else, I use my 6 1/2 x 18 inch ruler with shaded/colored 1/2 inch edge. It works well given the size of my cutting board. No need to run out and purchase a tone of rules.