Semperfli Classic Waxed Fly Tying Thread - Classic Waxed Threads (CWT) which have been designed specifically for fly tying for large Salmon, Predator, Streamer flies and for deer hair spinning with its great strength. Laying flat with a two core construction but can easily be split to create dubbing loops and they are strong threads. Semperfli worked with their Pro Team to get the correct amount of wax on each thread to hold materials but not clog your bobbin holder with Classic Waxed Thread. Semperfli created the highest quality polyester tying thread that you can have complete confidence in for your fly tying. Polyester Lots of Options for Colors 33.1oz Approx. Breaking Strain Denier Varies: 30 Denier up to 200 Denier Comes in either 120 yards or 240 yards.