UTC Ultra Thread 210 Denier - Ultra Thread has been engineered as a fly tying thread from the beginning. It is not an ",off the shelf", thread as are many others. All of Ultra Thread's characteristics were carefully chosen to enhance its tying performance. An excellent choice for saltwater flies and large streamers. Perfect for spinning hair on bass flies without being too bulky. Engineered specifically for fly tyingEven the spool was designed for fly tyingNylon materialSame strength as polyesterColors more intense than polyesterFlat thread with minimum twistsIdeal for large streamers, bass and saltwater flies