I am including this useful ruler again this year. It is by 'Quilt In a Day', Eleanor Burns. After many years of piecing, I know I do much better by sewing bias squares too large and trimming them to size. Cutting the triangles and sewing accurately seldom works for me. This ruler saves so much time because you trim the square to size after sewing and before pressing it open. You cut all four sides by trimming two. It is especially helpful when sewing small squares, like the 1" finished ones I've been doing.