SKB ATA (airline transportation association) rated cases are molded from ultra-high molecular weight polyethylene, the material specified by the U.S. military for cases and containers which must withstand the toughest field conditions. The case color runs through the material so scratches are invisible and the "poly" is impervious to all solvents, oils, fuels and acids. Every case detail is purposefully designed to optimize function. The molded-in configuration of bumpers and ribs are designed to absorb shock and vibration as well as provide protection for exposed hardware. The aluminum valance on SKB cases provides a reliable "tongue and groove" closure and a neoprene "o-ring" gasket keeps out harmful moisture. Bunk-bed storage with foam dividers provides separate compartments to store 4 rifles/shotguns up to 48". HDPE shell, weather resistant o-ring seal, stackable, bumper protected hardware, solid die cast zinc locks, ATA 300 Class 1 rated. Polymer wheels.