UV400 Protection is a filter that protects you between 99% and 100% of the Ultra Violet rays emitted  by the sun. Including UVA and UVB rays. This Means that your sunglasses will be able to block any UV rays with a wavelength of less than 400 nanometres.

It is very important when choosing your next sunglasses that they have this UV400 filter as it guarantees the necessary protection for your eyes since excessive exposure can cause eye damage such as cataracts and/or macular degeneration as well as skin cancer.