Rotopax Pack Mount Extension (1.75 Gallon / 4"x2.5"x1) RotopaX are the only EPA and CARB compliant fuel containers available for sale in the United States! This is thanks to a patented three-layer roto-molding process, along with specially formulated plastic barrier material to meet the governments&#39; new e RotopaX (patent pending) are proudly made in the U.S.A. by the original manufacturer of the first generation fuel and water packs. RotopaX are indisputably superior products.With RotopaX Pack Mount Extension, you can finally stack multiple packs together!New anodized aluminum.Use in conjunction with a RotopaX pack mount to extend its functionality.Sold individually.