I have two of these hats because the first one arrived incomplete without the front panel. Both were size large, but neither were actually large -one fit like a med-small and the other like a medium.They do provide sun protection for the face and the wide brim alone provides good coverage. The back panel gaps at the back when leaning forward. The back panel does provide good sun protection to the sides of the face as well, but the two side panels do not snap together under the chin. They need the front panel to snap to. The vents in the front panel and the hat itself do vent well, but the material itself does not breathe at all. Once you start to perspire, the material sticks to you and it is about as breathable as a plastic bag. So, probably not good for working outside while wearing unless you are doing very light activity.Overall, it does provide good sun protection. The front and side/back panels are removable to just wear as a wide brim hat, or with loose side panels for additional protection. There is a draw string in the hat band as well as one that hangs down for under the chin or behind the head to ensure a snug fit. It would be better if the material breathed.