If you know how pick your x's, just know that we're located in 4x country. Generally, you won't need anything else. If you didn't catch that drift at all, let's pull you in the boat. First off, your x's have nothing to do with Fly Rod or Fly Line weight (ie you bought a 9ft 5wt Winston--doesn't mean you have to get 5x leader). 0x, despite first impressions, is a nice, thick heavy leader built to handle throwing big flies to big fish. It won't stand up to pike, but just about anything else in freshwater, sure. Which means that 7x is a super-fine low-poundage leader that will probably break if you sneeze too close to it, but you can get it through the eye of a #24 midge. So now, when I say that we're in 4x country here, you start to get a picture in your head. You don't need extra-invisible leader to get our trout to swipe a dry off the surface, and they run big enough that you'll want some sheer strength in your leader to land them. But don't get carried away. You still have to present small'ish flies to our trout. So we land on 4x. Any questions?