Standardised UPF 50+ fabric. In other words, it offers maximum protection from the sun.
UPF is a sun protection factor (Ultraviolet Protection Factor) and is standardised worldwide.
It defines the protection level of a fabric and more precisely the proportion of UV rays it lets through.
In order to meet the standards, the UPF 50+ fabric has to block at least 95 % of UVA rays and 98% of UVB rays.