The Flash Back is cut to the width of the desired back or wing case. On a small nymph, a narrow strip leaves the legs and dubbing visible on either side. Attach it before tying the thorax, then fold it back toward the head once the body is in place. A strip that’s too wide will create folds at the tie-off point and unnecessarily enlarge the head. This material is suitable for flies where the contrast needs to remain confined to the top of the fly.