Base Curve: 8 Tr90: TR90 is thermoplastic material produced in Switzerland it is incredibly durable, flexible, and lightweight Polycarbonate: Polycarbonate is lightweight, comfortable, impact resistant, and provides UV protection. Anti-slip, adjustable, non-allergenic rubber nose pads. Unique, adjustable pantoscopic tilt hinges with easily replaceable parts upon normal wear-and-Anti-slip, adjustable endtips with stainless steel core for professional adjustment at the opticians.