Or as part of an ebook (4 patterns).

link to main thread

Clarification - you only need to work Rounds 1-16 (in the red box) once unless you want an extra long hat.

Quick and easy, reversible hat.

Make it as a beanie or with a longer ribbed section for cuff/slouch options.

Many thanks to the testers:

TeriLG
covelady
paulap
lynniebug
knitgrl
steffh82