Pepper's Speedline Polarized style is designed with monel metal frame that is lightweight and strong. Monel metal is a high quality optical material developed in the aircraft industry. Grilamid frame for total durability and flexibility. Spring hinges offer additional durability and comfort. Megol nose pads secure fit and resistant to slippage from lotions and sunscreen. Tri-acetate polarized lens features 2 acetate lens with a polyvinyl acetate layer sandwiched in between.