Wapsi UTC Ultra Thread 140 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. Excellent for the majority of flies, it is the perfect choice for size 2 - 16 flies. Due to its vibrant sheen and excellent color retention, it is a good substitute for floss on small flies. 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 size 2 - 16 flies