Leather is really abrasive on fiber, so the wax helps keep your thread from fraying. Waxed threads are stronger and stiffer than unwaxed thread while retaining most of the thread's smoothness feel and vibrant color. This thread can sew anything that can be sewn with waxed nylon or polyester strings. For example: Leatherwork, awnings, sails, shoes, saddles, bags, brief cases, gun cases, and luggage, etc. Professionally made with exquisite material, this flat wax thread is comfortable to the touch. Suitable for all kinds of DIY handicraft and leather products. With a Denier of 150, it is portable to carry and easy to store.