Hardside luggage features stiff molded construction in polycarbonate shells and creates the flexibility and strength for any travels providing full and thoughtful protections to your valuable gear. A piece of superior hard-side luggage can withstand the rigors of frequent air travel, as well as the extreme ranges of temperature your luggage undergoes in the hold of a plane, most are made from molded polypropylene or ABS plastic. Polypropylene is an oil-based plastic, also used to make car bumpers. It's extremely strong with a tough surface, and can withstand heavy impact. Most cases have highly secure metal frames with key and combination locks. Most hard-sided cases have straps in the lid and base so the two parts can be packed separately, and there's often a middle divider to separate the compartments and protect the contents.