The Costa Del Mar Fantail sunglasses are very similar to the Costa Del Mar Blackfin sunglasses. The only difference is that the frames are slightly smaller. For those anglers who prefer a smaller lens. The Costa Del Mar Fantail sunglasses feature a lens size of 59mm. The frame is also co-molded. The frame of the Fantail is made from nylon material. Making the Costa Del Mar Fantail sunglasses comfortable, durable, and ready for any angling or water adventure you have in store.