We will be camping in Colorado a good bit over the next few years, sometimes a month at a time. I have found this book to be rich with fly patterns to use there. There are plenty of comparison pictures between the naturals and his flys to fish when they are in a hatch. I have a plentiful library of fly tying and fishing books, I have spent most of my time, by far, with this book open. I re-read sections and tie flys from pages in it often. When I get to Colorado and fish the high country next time I will be ready to mimic the natural hatches because after reading this book the light bulb has come on. I will be able to tie my own fly patterns creating size, color, shape, and action patterns. All I will need to do is cast properly and present the fly with the right motion and depth. I have confidence the flys in my box or can tie at camp will be dead on. I am a top water fan, and this book satisfied that need as well. It is no wonder it was highly recommended on the forums at flytyers.com