From the Manufacturer:
The Omnigrid 1" x 12" ruler is used with compass points to draw circles (it has an extra 1/2" to accommodate compass points); it's also used to add seam allowances when sewing and quilting.
- Use with a rotary cutter or a straight-edge blade
- Edge markings for accurate measuring
- Laser cut edges for smooth, deep cutting
- Patented double-sight lines that show up on light and dark fabrics
- Heavy-duty durable acrylic material
- Left- and right-hand use