The Add-Three-Eighths, combines the speed of rotary cutting quilt pieces with the accuracy of using templates. With its 3/8in lip, the Add-Three-Eighths is specially designed for use with flannels or thicker fabrics. The specially designed lip on this ruler automatically allows 3/8 inch seam allowance to any angle for your rotary cutter. 1-1/2" x 12". #ruler #threeeighths #3/8 #cm38 #flannel #thickerfabric #blue