WAPSI UTC ULTRA THREAD 70 DENIER - FLY TYING THREAD * 2022 Stocks * UTC 70 | eBay
Understanding Thread Sizing, Construction, and Materials - Fly Fisherman
Using Denier to Standardize Fly Tying Thread | Global FlyFisher | It makes sense to have a standardization, which would eliminate much of the confusion that surrounds fly tying thread today.