Dennis,
Its for the twisted gut eyes on blind eye salmon hooks. I was buying the pre-twisted stuff from Partridge, but its something like $1.00 per inch. This way, it costs something like $1.00 for 3 yards. I bought those cards at Somerset last year, 30 yards for $5.00. You have to use 2 sections, so the 30 turns into 15, but well... you get the idea.
Anyway, take a 60" section, soak it in water for a while and tie a loop on each end. Loop the loops over the hooks [after clamping the tool to a shelf or something Ed

] and hang a weight in the "V" at the bottom. Start cranking the handle and as the 2 strands twist, they start twisting together, just like a furled leader. When it works its way to the top, you just let it sit there till it dries, and thats it.
I made 9 yards last night, in 15 minutes.
This thing is great, but I can see where I am going to exhaust my gut supply in a hurry

Of course, tying the flies takes time, so I probably have enough for the next few years
CJ