The Omnigrip 10-1/2" Square Ruler set includes: 6-1/2", 8-1/2" and 10-1/2" rulers. These rulers have all the features of an Omnigrid ruler with a patented non-slip backing for added stability. The fluorescent ink pigment enhances visibility in low-light conditions. Highlighted precision markings allow for easy viewing on all colors and patterns. 45° diagonal lines help to center and align patterns while squaring up quilt blocks. Additional 1/2" seam allowances included on two sides of ruler. 1/8" thick optical-acrylic is laser cut to work with rotary cutters and craft knives. Item Number: RN65105S Highlighted 1/8" ruler markings (6-1/2" & 8-1/2") along 2 edges of ruler for measurement and placement accuracy 1/4" dot and line grid or line grid pattern throughout rulers Perpendicular dot and line grid forms square outlines to aid in squaring up quilt blocks 1/2" additional width includes seam allowances Patented non-slip backing to help keep ruler in place while cutting Optical-grade acrylic with smooth, laser cut edges for rotary cutters and craft knives 45° diagonal lines for aligning pattern while squaring up quilt blocks Square cut sizes for on-point half-square corner setting triangles and quarter square side setting triangles printed on 10-1/2" ruler