Rotopax fuel containers allow you to bring more gas with you on your backcountry missions. The 4 gallon tank is the biggest of the lineup, and fits perfectly on the Big Days Headache rack. It attaches to the Molle panel using the Rotopax mounts, also available in the Big Days store. Want a smaller setup? Check out the 1 gallon option that fits right on the Big Days riser, or the 2 gallon that also fits on the Headache rack. 4 Gallon CARB/EPA 50 State Compliant Fuel Container with a 10 Year Leak Free Guarantee. Fulfilled by Rotopax in Ogden, Utah.