The Omnigrip 10-1/2 x 10-1/2" square ruler is 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 10-1/2 square ruler has the following standard Omnigrid / Omnigrip features: Patented non-slip backing to hold ruler in place during cutting Edge markings for accurate measuring Laser cut edges for smooth, deep cutting Patented double-sight lines that show up on light and dark fabrics Diagonal line for triangle cuts Markings for half-square and quarter-square triangles Heavy-duty durable acrylic material Left- and right-hand numbering and angle system