Frame: TR90 is a thermoplastic developed in Switzerland that is extremely durable, flexible and lightweight. Lens: Polycarbonate lenses are robust, break-resistant and offer excellent UV protection. Spectacle shape: Square/Base 8 Polarizing lenses are particularly advantageous for sports and leisure activities. They absorb dazzling light reflections, enhance contrasts and improve colour perception. Optimal face shape: round or oval Prescription glasses possible Possibility to change lenses to prescription lenses. The best way to do this is to contact the optician of your choice.