UNI 17/0 Trico Fly Tying Thread- Many of todays threads are often too bulky for tiers who work with hooks smaller than size 20. UNI Products, the leader in innovative spooled materials, comes to the rescue with the 17/0 Trico thread. This extra-fine (40 denier), white, polyester thread, is amazingly strong for its diameter. Perfect for caenis, trico, tiny baetis, midges, micro-caddis, and realistic patterns. Hit with a permanent, Copic waterproof marker to get the desired color. Breaking strength is 4 ounces. UNI Trico 17/0 comes in 200 yard spools.