The black impact resistant polyethylene Kimpex Flexi-Trunk is a great addition to your ATV.  It has a storage box that is large enough to fit a small full face helmet and even has room to carry a small 4.7L gas container.  It comes complete with a truck connector for rear light.

The Kolpin Gun Boot IV is the Cadillac of hard carrying cases for your ATV. The Gun Boot IV is capable of handling guns up to 49" long with a larger storage area to handle rifles with 50mm scope and sling. Plus, this gun boot has a dust-proof, water-resistant, and protective case and will handle both right and left handed bolt action rifles.

These lockable, high-density polyethylene bracket mounts allow Gun Boot IV or Gun Boot 6.0 to be snapped quickly to either side of any ATV with rack at a 45° angle.

Kolpin's Rack Bracket is heavy metal construction that offers quick release of the Gun Boot case as well as lockability.  Its rubber armor coated ring holds the Gun Boot case while a provided locking pin keeps it in place to prevent vibration and movement.  A padlock may be used for extra security. 

Kolpin's revolutionary design secures your Kolpin Gun Boot to any ATV. Simply attach bracket to ATV rack (universal fit mounts to virtually any rack) and lock the Gun Boot into bracket by pin or padlock.