Tifosi Seek FCA great running performance depends on clear vision. The Tifosi Seek FC eyewear features shatterproof, polycarbonate lenses that offer 100% protection from harmful UVA/UVB rays, bugs, rocks, or whatever else comes your way. The frames of these running glasses are made of Grilamid TR-90, a strong, UV damage resisting nylon. Lens installation/removal is fast and easy. Rubber ear and nose pieces provide a no-slip fit. For your comfort, ear pieces are adjustable for a customizable fit. Certain Tifosi Seek FC products feature Fototec lenses that rapidly tint as needed, adjusting to changing light conditions and providing exceptionally clear vision and protection. One size fits most.