The Omnigrip 20-1/2" square has a diagonal line for triangle cuts; the ruler has extra ½ 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 20-1/2" 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
Heavy-duty durable acrylic material
Left- and right-hand numbering and angle system