The Superflite bias tapes are cut diagonally with the weave the fabric, giving them more stretch to lay down nicely around curves and edges.  Because of the way these tapes are cut, there is a seam every 3 feet in the roll, where the fabric has been pieced together.  The rolls of bias tapes are only 25 yards in length, whereas your standard and pre shrunk tape rolls are 50 yards in length.