Benjamin M.wrote a review of Anon Helo 2.0 Helmet on January 16, 2019
My head is a tiny bit over 21 inches and the small barely fits. I'm keeping it since it works, but I can't throw a beanie on under it like I generally like to do. If you're at the higher limit for sizing, I'd recommend getting a size bigger and using the BOA adjustments. Overall though, it looks nice and strap is easy to get on and off.