I just bought a kids hat with an adjustable Velcro back. Fits V great. He does have a head in the 90+% though...so.....lol.
All kidding aside, it does fit great. To it at Sports Authority.
I have one from Walmart that is just simple navy blue. It fits DS's head but it slides down over his face a lot.
It is not a good cover from the sun though. It doesn't cover his ears or neck. Use a bucket hat for that, or one that has a neck cover (I plan on getting on of those soon).