There is a discreet tightening system for adjusting this cap
Fabric allows moisture, generated by the head, to escape
Is my cap UV protective?
Although the fabric has a UPF coefficient of more than 50 (ie only 1/50th of the sun's rays pass through), this cap is not officially anti-UV according to applicable standards because it does not cover the back of the neck, which is a necessary condition for the certification. However, your head will remain well protected