Semperfli Cobblers Wax is the perfect match for primrose fly tying threads and primrose Pure Silk from Semperfli to produce the perfect Greenwells color for your flies. Each spool comes with a leatherette patch to keep your cobblers wax in pristine condition. Semperfli manufactures this themself using top quality ingredients. Simply take your thread and run it through the cobblers wax to get that perfect greenwells.