YOUR noggin? Have you stood beside me in the past Wayne? I'm not exactly a petite, dainty flower. 
It's not TOO big a deal, since I don'tplan to ever have a full suit. This helmet was acquired through trade, and I'd like to set up a bust to display it ... and some chest armor with my lights in them. I just wanted to try it on, and couldn't believe that something this big (larger than the DPs) was so snug.
And for the technically inclined (liking facts and figures), I don't know my *exact* hat size ... but I know a size 7 3/4 is too tight for me to wear comfortably. 
ATM