TYR Flex Frame Swim Mask. Do what you love with the Flex Frame Swim Mask. Featuring an extremely flexible frame, the molding capabilities of the Flex Frame Mask fit various facial types. The LGFFSA also provides wide peripheral vision for excellent siting, and it is engineered with polycarbonate lenses for maximum strength and clarity with minimal bulk. Featuring a silicone gasket for a watertight seal, speed adjustment for quick and easy sizing and a unibody design, this swimming mask is perfect for recreation. All polycarbonate lenses include full UVAUVB protection.