Confusion reigns when metal for trolling line is used in the Lake Michigan mix. It's mostly a problem of defining what line is what. Metals; STAINLESS wire: is very strong and skinny so it cuts thru the water and has weight to it. Fish bud, PK once picked up a used reel with a solid stainless wire on it. He used it with a pound ball and found the wire getting prone to curling up when slack came in the line which also made it prone to kinks. Kinks are the nightmare any wire line user has to be careful of. They can be bad enough that the line will break easily on the next fish. Kinks are bad whether they are in solid line or seven strand stainless that comes in 300 foot spools from Fleet or, have the bulk line spun on at Algoma Hardware. I use seven strand 30 pound for pound balls (sometimes called pump handle rigs here on LL), and I use 20 pound for wire dypsies. Both are used interchangeably on roller guide rods that have expensive tips that prevent the dreaded line curl. COPPER: also comes in 30 pound and heavier weights and is an alternative to lead core. These lines get spoons deep in a stealthy manner without heavy weights or turbulent diving discs. I'm a fan of lead core but also like my newer copper line sent out on a heavy duty planer board, (my old yellow birds can't cut it with longer core or copper). They both need a higher capacity reel as some mentioned already. Copper can get kinked too but is a softer metal than steel. It's new to me, but some use heavy standed steel in heavy weights instead of copper, which I know nothing about, that was mentioned by an earlier poster. Spiney Water Flea season is coming on and lead core, copper, and wire are more resistant but not immune to that plague. Thirty pound mono on downriggers has a lot of blow back but it does shed fleas better than power pro. I'll be out there with the rest trying for 40 pound kings! Best of luck out there .......Jim.