Highly regarded Semperfli Nano Silk fly thing thread is super strong, super smooth and the choice of professional fly tiers worldwide.
Semperfli Nano Silk is GSP thread making it incredibly strong for its diameter. Nano Silk gives you strength without bulk, awesome stuff. 50 Denier Semperfli Nano Silk is equivalent to 12/0 in terms of diameter but way stronger than other threads.
Each spool of Semperfli Nano Silk has 50 Meters per spool. Breaking strength is 4.2lbs. Nano Silk lays perfectly flat with a bit of counter clockwise twisting, 50D is ideal for flies sized #6-16.