I also have an extremely large head.... 25.0". I got a factory diver custom made for me as even a XXL wont even get over past my ears. In fact it ended up being too wide for my head shape (its more long than round), but that was easily fixed. I am also looking into getting a custom Oxygn, as they now do custom sizes by cutting it down the middle and adding an extension piece. These are obviously both full face options.