Salmon were only running 18 -25 lb but these worked great. No knotting of line or breakage of swivels. Got five salmon and one 20 lb halibut last summer.
I tie my own leader (8 lb Berkley Vanish fluorocarbon line) about 4 feet long so these worked excellent when trolling fast (3+ mph). No line twist at all. I bought the 6 bead chain swivels.
Highly recommend for saving fluorocarbon line (in my case anyways) or probably any line when line twist can be an issue.
These may also work as small flashers to attract the fish as I noticed the sunlight reflecting off of it in the water when doing a check of the lure.
Chain swivels to large for my use. Used to buy these locally and they were smaller and easier to use. Picture in catalog doesn't show them as large. Not satisfied with them but can't find them anywhere else.