Airflo's Euro Nymph Rollers are engineered to prevent droppers from twisting your tippet during casting and fishing. They're designed to enhance fly movement, as the dropper isn't rigidly fixed like it would be with direct knotting to the leader. These rollers also simplify changing droppers/rigs, as they can be prepared at home. By using an Euro Nymph Roller, you'll reduce breakages, as the roller moves along your leader and up/down to a stop knot, making droppers more forgiving during hard takes or double headers. Suitable for both river and lake fishing.