There are a lot of numbers in fly fishing, and some of the numbering may not make sense to the uninitiated—or to the initiated, for that matter. A higher number means a smaller hook, yet the opposite is true when it comes to fly rod weights. It can be a little counter-intuitive. But we fly-fishers pursue a very wide range of species, from tiny sunfish to bluewater tuna, so specialized gear is necessary, and you have to categorize it all somehow.