The tippet rings are made of Nickel Stainless Steel, which has strong corrossion resistence and duratity, so you don't have to worry about using them in any harsh environment. They are incredibly small and the black nickel should help cut down what little visibility could happen with these microscopic rings. Break strength 25lb(2mm) and 45 lb(2.5mm), they are strong enough for any fly fishing. The rings make changing or replacing tippet easy and don't effect casting, turn over or presentation, so they can not only save time, but a lot of expensive tapered leders. What's more ,thick profile and absolutely round circumference to prevent line from demage and provide best knot strength.