Tippet rings can be used for tying leaders. Tippet ring is usually made of steel and have small diameter designed for using with thin fly tippets. A very convenient way to attach fluorocarbon and monofilament as it may be quite tricky to knot them straight against each other. Helps tying droppers also. A must have tackle for nymph fishing, whether you fish with french nymphing technique or some other modern nymph fishing style.