Single Horse Driving Lines 1.9cm Wide Beta, 6.1m Long. The lines have buckles on the bit ends with double stitching. Reins are made from beta or biothane. Beta is a synthetic leather. It has the look and feel of leather, but is stronger and easier to care for. All you need to do is wipe it down with a little soap and water. You can also submerse it in bucket of water or spray it off with a hose. No oiling and no mould.