The Clearly Perfect Slotted Trimmers are an easy, efficient, and accurate way to square up half-square triangles. Simply align the seam of an unpressed half-square triangle with dashed lines and trim all four sides. The edge slots allow you to trim off the dog ears at the same time! It can also be used for squaring up hourglass quilt blocks, strip piecing half-square triangles, strip-tube quilt block construction, and fussy cutting. Try the Clearly Perfect Slotted Trimmer A2 for larger sizes.