The Omnigrip square ruler has a diagonal line for triangle cuts, It also has an extra half inch on two sides for seam allowance. This ruler is ideal 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.Details:Clear with neon and black markings12.5" x 12.5"Edge markings for accurate measuringLaser-cut edgesLeft- and right-hand numbering and angle systemDouble-sight lines visible on light and dark fabricsNon-slipAcrylicFor use with rotary cutter or straight-edge blade