Australian/New Zealand standard for sun protective clothing
Requirements for sun hats
To claim or display a UPF rating, hats must provide good sun protection and be one of the following designs:
(a) Bucket (at least 6cm brim width)
(b) Broad brimmed (at least 6cm brim width for hats with a 56cm circumference and a 7.5cm brim width for a circumference greater than 56cm).
(c) Legionnaire (shall have a neck flap providing coverage for the ears and back of the neck to the collarbone/shoulder).
(d) Alternative hat designs providing protection and shading at the crown, face, ears and neck are also acceptable.