Ultra GSP is the strongest thread on the planet.
Boasting steel-like strength for its weight, this thread really lets you put the pressure on! Our gel spun polyethylete is supple, ties flat and is available in the largest selection of sizes and colors. 50 denier GSP is perfect for tying the smallest trout flies with a minimum of bulk. Our new 75 denier is the ideal choice for all trout flies. It is small enough to tie tiny dry flies and strong enough for the largest trout streamers. It is an excellent all purpose fly tying thread. GSP 100 has all around versatility for fresh and saltwater flies. It is an excellent thread for bonefish and permit fly patterns and our favorite pick for trout and smallmouth bass streamers. GSP 200 is the best size for big deer hair work or when you really need to crank down. 50 Denier Gel-spun polyethylene, the strongest thread made, with steel-like strength. Use when the strongest thread in small diameters is required. Use only with ceramic or ruby tipped bobbins. 50 yard spools.