Hat Rain Protector

What is the differnce between the one on this page and this one http://www.amazon.com/Western-Adults-Cover-Crown-X-Large/dp/B00HFZC4HU/ref=sr_1_3?ie=U

Hiw di I know what size I am ordering? Is there an option?

What size for Australian style small and med hats? 4 in tall crown, 2 in wide brim. My head is 22 in in circumference.

Hate to bother ya'll with more questions, but here's another: will i want an xl for a 5" brimmed gus style rodeo king? thanks a bunch.