UV400 PROTECTION-Lenses block 99% or 100% of UVB and UVA rays.UV 400 indicates an eye protection item that has been optimized to prevent eye exposure to both UVA and UVB radiation. One of the biggest differences between UV 400 protected items as compared to other items that protect against the sun's radiation is the fact that UV 400 protected items are capable of blocking light rays as small as 400 nanometers.