Use the straight side of this double strip ruler to cut 2-1/2in strips. Sew these strips together to create a 4-1/2in wide strip set. Or use precut strips that are so popular today. Use the other side of the ruler to cut three 90 degree triangles at once that finish to 4in. Multiple layers can be cut at one time. The key holes in the ruler enable the rotary cutter to cut the angled sides without damaging the ruler.