DescriptionPro Sportfisher Pro Trout Systems Pro Stone Clinger Nymph backs are UV gloss domed, easy to use nymph backs. Each back contains 18 body/thorax/head sections that are easy to tie in. These realistic clinger nymph backs great looking and allow tiers to create great looking durable flies that catch fish. Medium size clinger nymph backs are designed for hook sizes 10-14.