Playing airsoft/paintball outdoors, in the heat of the sun, may not be all that pleasant. The facemask and all of the protective gear just makes it worse. But a little bit of shade could go a long way. That's where the Safari Boonie Hat comes into the picture.
Unlike a helmet, which doesn't shade the side of your face and shoulders, the wide lip on the Safari Boonie Hat shields a lot more areas on your body from the sun. And one with back protection, such as the one shown in this article, protects the back of your head and neck from BB and paintball shots.
This Safari Boonie Hat also has snap buttons (see photo below), which lets you button up the lip on two sides, in case you want a little more sun. Meshed vents allows air to circulate at the top of your head.
It comes with a quick release strap (see photo below) that can be tightened or loosen on the fly. This strap will keep the hat on your head even during a firefight.
The biggest concern for airsoft/paintball players is how well this hat fits over a facemask. The photo below shows a large Safari Boonie Hat on top of a Scott Vectra facemask. It is not strapped on tight, at the time of the photo. As you can see, it can fit over the facemask visor. It'll fit just fine without the visor as well, though you might want to use a different size to fit your head.
The Safari Boonie Hat is made out of 60% cotton and 40% polyester.
Even better, the Safari Boonie Hat will improve your concealment in the environment. Used correctly, it will assist in "breaking up the recognizable outline of the soldier's head". "[Special Operations teams] favored the soft boonie hat to a helmet since it was cooler to wear, did not interfere with hearing and broke up the outline of the soldier’s head assisting with concealment. The brim also provided a measure of comfort against monsoon rain and hot sun." These are direct quotes from Wikipedia's page on "Boonie hat" and from the "Boonie Bust Up: A Tale of Seven Boonie Hats" article (see "Related Links" below).