The brim size ranges from 2 1/4" on the small to 2 3/4" on the 3X to remain proportional to your head size

As a final point

UPF 50+ Sun Protection

This is a well constructed

Henschel - Olive Distressed Duckbill Cap Size:MD The brim size ranges fromThe Henschel olive distressed duckbill cap is a very comfortable and stylish ivy hat. Constructed and woven from 6 panels of material, this hat has a very rugged well worn look to it. Made of 60% cotton, 36% Polyester, and 4% PU, it is soft to the touch and instantly gives you that favorite old hat feel. Inside it is lined with soft black said material, and a sweatband that is quadruple stitched. A bestseller for a reason, look and feel is everything.