The Add-A-Quarter Ruler PLUS combines the speed of rotary cutting quilt pieces with the accuracy of using templates. Once your paper piecing seams are made, fold back the paper on the stitched line, align the Add-A-Quarter Ruler against the folded paper line, and the Add-A-Quarter Ruler will automatically add the customary ¼" seam allowance to any straight angle while providing a straight edge for you rotary cutter. The PLUS version of this ruler has one edge that is tapered for folding back foundation paper to allow for fabric bulk, so there isn't the wobbling of the flat version. This is the 2” x 12". There are a variety of sizes in this ruler.