Piggyn, the thread diameter is .04. I am not positive of the # test but it isnt very strong and I would guess it at about 1/2 pound. It does not spin or coil up near as much as the line I used before (trilene micro-ice) plus it is thinner for those finicky fish. The jig also stays dead still in the water (no spin). I do not use a mono leader, but it is probably a good idea. I havent fished in extreme cold weather, but the thread hasn't froze up with high's in the mid 20s. It is also a lot cheaper and you get twice as much line as the normal ice line.

So far I like it and am going to keep using it