Neon Square Ruler, 16-1/2" x 16-1/2"The Omnigrip 16 1 2" square has a diagonal line for triangle cuts; the ruler has extra 1 2" on two sides for seam allowance. In general, Omnigrip square rulers are used for secondary cutting of strips, and to square up finished quilt blocks Use for quilting, sewing and crafts or any DIY project that calls for cut fabric Use with a rotary cutter or a straight edge blade The 16 1 2"" square ruler has the following standard Omnigrid Omnigrip features: