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. One-piece, internal Spring Hinge fitting broader range of headwidths. Anti-slip, adjustable, non-allergenic rubber nose pads. Anti-slip, adjustable endtips with stainless steel core for professional adjustment at the opticians.16º lens angle adjustment to cater for different riding modes: road, off road, TT racing.