If you buy a particular knotless leader, you're not stuck with that same tippet size. It's very easy to change your tippet sizes. And this confuses a lot of people, but it's really not that difficult. I'll show you how I do it and see if that works for you.
So I've been fishing in this stream with a 7-and-a-half foot 3X tippet. The leader has a 3X tippet on it. I want to go to a size 14 fly. The fly I was using was a size 10, it looks a little big. I want to go to a size 14 fly, so I need to change this 3X leader to a 4X leader. How do I do that? Well, here's what I do. I carry a bunch of tippet spools with me. They hang from my fishing pack and there are different sizes there. And I'll take maybe a couple of feet of this 4X tippet material that I want to add to my preexisting leader.
Now, don't cut leader material with your teeth, your dentist will give you hell. Don't do what I do and use your snips, ok?
What I do, I don't really know what the diameter is at the end of this leader because I have changed flies and stuff, but it's really easy to figure out what size it is because what I can do is I can lay my piece of 4X alongside this leader and kind of eyeball the two sizes. And what I wanna do is get to the point where that knotless tapered leader is tapering up to the point where it's just a little bit thicker than that 4X tippet. So I'm going to kind of eyeball it and I'm going to slide it up there... right about there. It looks a little thicker. So what I'm going to do, is I'm going to cut this off - remember use your snips - I'm going to dispose of that piece of nylon properly. I'll throw it away when I get home, not on the stream.
And now, I can take this piece of 4X and I can tie it onto this leader and now instead of a 7-and-a-half foot 3X, I have a 7-and-a-half foot 4X leader. If I wanted to go even finer, what I could do, if I was fishing 4X and wanted to go to 5 and I already have a knot in there. I can just cut this 4X piece back to 6 or 7 inches and then tie a piece of 5X on the end. So by moving back and forth with just having a bunch of tippet spools, you can modify the knot-less leader.
I'll start with one knot-less leader at the beginning of the season and I might not change that leader for, I don't know, maybe 2 or 3 months, despite the fact that I've made hundreds of tippet size changes and fly size changes. But you can work with the same basic leader butt section that's tapered for along time just by modifying your tippet size.