Choosing the right size for your ATV rear seat bag depends on your budget, your lifestyle, and your expectations. You can start by opting for a medium-sized one just to see exactly how all your stuff fits into the scenario. A medium-sized bag should be more than enough for a single person going on a weekend getaway camping or in the woods. We do recommend opting for larger sizes with additional detachable compartments if you plan a true trip or you need to keep all your vacay items with you.