Thanks Jared. Actually it turns out that it's actually two lines spooled one after another. I was able to find some pics of other similar Skagit lines and they do look super thick, these are definitely not those.
I'm going to throw them on some empty reels and see how they fly!
A 575 gr line is just a little over the weight of a 15 weight fly line, It might be good for throwing the big poppers used for bill fish, if you happen to have a single hand 15 wt lying around. I would recommend you take 8-10 $100 bills and throw it in the fire with your fly line. Otherwise you may get into spey fishing which will cost you some REAL money!!!