SemperFliClassic Waxed Thread has been developed after examining the traditional waxed threads used by fly tyers world-wide. The polyester threads have the innovation that always occurs with Semperfli products. They extruded the polyester thread so that it is flatter than other threads giving more grip to prevent material slippage. With a light wax coating to provide grip but not enough to clog a bobbin holder. Strength has always been a baseline consideration at Semperfli so the 8/0 is 40% stronger than comparable threads. Finally, they made sure the flat profile thread was easy to split!