Between the main line and leader that is. I use P Line hydrofloat for my main line with a flurocarbon leader and have used a barrel swivel between the two and I have also just tied them together with an albright knot. Does one have an advantage over the other? I am currently reading Dave Vedders book on jig fishing and see illustrations showing both setups. So far though I havent read about any advantages of one way over the other.