One of the first things you learn off the bat when you get into the sport of 4-wheeling is that helmets are required equipment at virtually every legal 4-wheeler trail in the Northern hemisphere.
A 4-wheeler helmet will need to fit correctly in order to provide maximum protection for your head. If you can pull on a helmet and take it back off without having to spread it open a little, then that 4-wheeler helmet is to big, and is just as likely to pop off if you take a hard bump.
When you pull on a properly fitted 4-wheeler helmet, the inside padding should fight snugly around your head and cheeks. It's designed to block out wind noise, and it should stay stable if you shake your head from side to side. In addition to your helmet, there are also helmet accessories that you can buy to give your 4-wheeler helmet a customized feel.
Visors can add extra sun protection for your eyes, as well as block rain from obscuring your vision. Top vents and mouth vents can also add much needed air flow on those especially warm summer days. Cheek pads can eventually become pretty rank smelling after months of use, so why not keep an extra pair on hand for when you want to freshen up. Also, don't store your riding helmet in your garage near any kind of chemicals that give off fumes such as gasoline. The fumes will break down the glues and resins that hold the foams and lining of your helmet in place.
There is a full line of both 4-wheeler helmets and accessories available, if you don't see exactly the item you want, just ask Raceway; chances are the item can be obtained for you!