I had to shorten my belt by 2 inches. Although no instructions were included, there is a lever on the back of the buckle. Pry the lever with a flathead screwdriver to loosen the leather strap. The plane has a set of teeth that are attached to the skin. If you are cutting a length, make sure it is cut at a right angle and not crooked. I cut the leather with a utility knife and a new blade and cut through the leather with no problem. By the way, the strap itself looks like two pieces of leather about 3/16 inch thick sewn together and feels solid.