[Water Warrior 2]

Helmets do not come in mens and ladies sizes. They just come in a variety of sizes so find one that works for you. Be aware that some helmets come in different shapes for different head shapes. One manufacturer may lean toward a rounder head shape while another may be more inclined to produce a helmet for a narrow head. Always get the helmet that fits the snuggest without being uncomfortably tight. The better the fit the more you will want to wear it.
I am presently on my 3rd HJC helmet and an reasonably satisfied. I did however try on a Shoei Multitech helmet. There was a completely different fit to the Multi that was very surprising. My exact headshape and a size smaller which meant a slightly smaller lighter shell for less neck strain. Can't wait for my present helmet to get a little older and due for retirement.
Oh, also be aware they do not "ALL" follow the same sizing criteria, A large HJC helmet may be some one else's medium or extra large.
Try on all the helmets you can. Some dealers will allow a test ride with a helmet or a return policy if the helmet doesn't work out so well.