Only .004 thick, Thin Skin works best when used on flies with a size 18 or larger hook. Its a stretchable, transparent material with a matte finish on one side and a shiny finish on the other. Thin Skin is easy to cut and work with, thanks to its backing. Some excellent applications include nymph wing cases, as well as backs for scuds, sowbugs, crayfish, and shrimp. Color: Mottled Natural. Cancer and Reproductive Harm- www.P65Warnings.ca.gov.