These rulers combine the speed of rotary cutting quilt pieces with the accuracy of using templates. Once your templates are made, the Add-A-Quarter & Add-A-Eighth, with the specially designed lip, will automatically add the customary 1/4" or 1/8" seam allowance to any straight angle and provide a straight edge for your rotary cutter. Reduces the time and effort and is invaluable for both hand and machine piecing. Also good for trimming off the excess fabric for your 1/4" or 1/8" seam allowance.