The all new TFlex sunglass features an innovative "Temple Flex" hinge system. This revoltionary technology replaces conventional screws and rivets which can wear out and break thru time. The Temple Flex hinge is extremely durable while still maintaining a comfortable custom fit for most face types. Add the optional thick nosepiece to accommodate narrow nose bridges and prevent lash crash. The TFlex Sunglass easily converts from a sunglass to a goggle by retrofitting with a foam insert and a TFlex hybrid goggle strap. There is a 1 year manufacturer's warranty and a lifetime service guarantee.