x4 I keep a spool of 40lb. Maxima on hand at all times. Attach a pc. to the line using a nail not. (sometimes, I add a drop of Zap-A-Gap, but I've never had one come undone without it) I then, to reiterate, form a small perfection loop as close to the fly line as possible. Done! Why 40lb? You don't want this interface to be soft, or it will create a "hinge" effect between the leader and line. When I'm half-asleep, making one of these connections at 2 in the morning before a fishing trip, it can take 1-2 attempts to get the nail not looking pretty.