Most of the inside at the crown is exposed straw. A small panel in the front of the crown appears to be a synthetic material.
Not really a strap, but a cord that can be adjusted for tightness. I've been hit by a dust devil while wearing this hat. The hat stayed on my head and survived.
The hat brim is 5in from the inside hole, the head hole is 7in around
That circumference or crown measurement for this hat is 22.5 inches.
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