So why tippet, if you already have a tapered leader? Isn't it just another way for the industry to nickel and dime you to death? Well. Perhaps. However, if you bought that tapered leader, you'll notice it's rather expensive for nine feet of monofilament. So why on earth would you want to waste some of that beautiful taper every time you change flies? The answer is that you don't, when you really think about it. Hence the need for tippet. You'll want your tippet to match your leader or a size smaller (4x tippet to 4x leader, 4x tippet-5x leader for example) so that you waste the relatively inexpensive tippet tying on flies instead of the tapered leader. Now, for the uninitiated (Note, I didn't say the willfully ignorant), tippet classification can be rather confusing. Let's clear some of that up: remember, it has nothing to do with the weight of your fly rod or fly line (using a 3x leader because you have a 3 weight rod will end in disaster). Also, bigger numbers doesn't mean stronger line. 4x = 6ish lb test. 0x = 13ish lb test. The higher the number, the more delicate the tippet. There, consider yourself informed, so now you can make an intelligent decision.