'Mad as a hatter' probably owes its origin to the fact that hatters actually did go mad sometimes due to the mercury they used

and a Coolmax™ sweat wicking band inside

Whether you need extra sun protection for gardening or you're looking for an extreme condition hat to add to your outdoor work attire

or going around town

Flexfit - Black Premium Fitted 210 Cap Travel Hats 'Mad as a hatter' probablyThe Flexfit Premium Fitted 210 is a pro baseball on field shape with a flat visor. Featuring a 3 3 4" crown, moisture absorbent pro headband, and bottom stitching for lasting durability it is your solid baseball style. Made of 83% Acrylic, 15% Wool, and 2% Spandex S M (6 7 8" 7 1 4") L XL (7 1 4" 7 5 8")