What is hatching? Do you have the right fly? Matching The Hatch is the essence of fly fishing. The Guideline Caddis fly shows that you are serious about it. The cap is made of 47% brushed cotton twill, 25% polyester and 28% nylon. Velcro closure in the back. The color is Tangerine (pumpkin) in front with stone color on mesh. One size fits most.