The 90° Double-Strip ruler is one of a range of Strip Rulers that are designed to make cutting Half-Square-Triangles, Quarter-Square-Triangles, 90° Triangles, Trapezoids and more from 2½" wide strips quickly and easily!Use the straight side of this double strip ruler to cut 1 ½" and 2 ½" strips or use the pre-cuts that are on the market. Sew these strips together to create a 4 ½" wide strip set. Turn-a-Round the ruler to cut multiple shapes that finish 4". Multiple layers can be cut at the same time.