A thicker material than polycarbonate or Trivex, CR 39 is a type of plastic that glasses lenses are traditionally made from.
Polycarbonate is an impact resistant plastic material.
It is often used in safety specs, as it's less likely to fracture than regular CR 39 plastic lenses.
Trivex is a lightweight lens material that is much stronger than plastic or glass.
100% UV resistant as standard, this material is ideal for glasses, in particular those for kids, due to its durability.