First, you get UV protection because the material from which we make our caps employs a ripstop weaving technique to increase the density of the fabric. Densely woven fabric offers you superior protection against UV rays.
Second, UF PRO caps protect you because the fabric itself has UV protection built right in. Depending on which one you buy, the fabric will be either synthetic PolyCo or semi-synthetic NyCo. Both are very good at absorbing UV rays and preventing penetration.
Third, you get still more UV protection by choosing UF PRO caps in a dark colour. The darker the colour, the better the absorption of UV rays.