What it is
The Hareline Stonfo Thread Splitter is a stainless-steel fly-tying tool for splitting tying thread cleanly and predictably. It’s rust and corrosion resistant, with a sharp, thin blade and a precise splitting mechanism so you can open the thread without shredding it. The ergonomic handle grip keeps it steady when you’re working close to the hook.
What to tie with it
Use it to split flat thread, insert dubbing or other fine fibers, and then spin the thread back up to make a tight “dubbing rope” right on the thread. It’s also a clean way to start and control delicate dubbing loops when you want a sparse, even blend for dry flies, nymphs, and textured bodies.
Flies and the fish they're for
This is a technique tool rather than a fly-specific material, so it shows up anywhere you want a very controlled dubbing noodle or a fine, buggy loop. Thread-split dubbing is a staple approach for small dry flies that trout and grayling sip in slower water, and for nymphs where you want subtle movement and texture for trout in rivers and tailwaters. The same split-thread and loop methods also translate to small stillwater trout patterns when you’re aiming for a soft, natural profile.