RotopaX solve a specific problem: carrying fuel and water on the outside of a vehicle without it leaking, rattling or being easy to steal. The flat, stackable shape is the whole idea - packs sit tight against a rack instead of rolling around like a jerry can.
Construction and compliance
RotopaX use a patented three-layer roto-moulding process with a specially formulated plastic barrier material. They state their fuel containers are fully compliant with applicable CARB, EPA and ASTM standards, and describe themselves as the only rotationally moulded EPA and CARB compliant fuel containers sold in the United States. Products carry a full manufacturer warranty.
Sizes and mounting
Packs come in 1, 1.75, 2, 3, 4 and 5 gallon capacities across fuel, water and dry storage. Every pack uses the same mounting system, so you can mix fuel and water on one rack. Mounts are sold separately: the Standard Pack Mount, the DLX Pack Mount, and the Gen 2 LOX Pack Mount which adds locking. Extensions let you stack packs on a single mount.
You will need somewhere to put them
A pack mount bolts to a flat surface or a rack. If you do not already run a bed rack or roof rack, sort that first - it is what the whole system hangs off.