Structured or unstructured? The structured are Flexfit caps that have elastic all around the inside of the cap, with a forward area that is a little more firm and... "structured."
The unstructured use a buckle/strap closure on the back of the hat and are more deformable up front.
I can have both types made (do a 50/50 run), but curious who prefers what. I personally like the Flexfit, though it sometimes squeezes my huge head.
Structured Flexfit:

Unstructured/buckle and strap:






