Omnigrid s square rulers are used for secondary cutting of strips and to square up finished quilt blocks. You ll find Omnigrid rulers ranging from 2-1/2 square to 15 square. Many of the square rulers also feature a section of 1/8 grid. They are made of heavy-duty durable acrylic material and feature a left- and right-hand numbering and angle system. There are patented double-sight lines that show up on light and dark fabrics so cutting is a breeze.