As for casting,we all use swivels to prevent line twisting on retrieving harnesses.We also use swivels when trolling harnesses for same reason.For cranks we use only duo snaps.Make sure wire projection on clip faces upward on your crank.If faces down could scratch the plastic lip of the crank and restrict the action on your crank.This was pointed out to me several seasons ago.Proof was you can see a semi circle on lip of crank where snap was scratching the surface.