Curv Material - Layers of woven polypropylene are formed into self reinforced composite sheets providing superior durability while being extremely lightweight. * Spinner Wheels - Four wheels...zero effort, four multidirectional spinner wheels allow 360 degree upright rolling in multiple directions so there is no weight on your arm. * Push button handle - Locks when fully extended so you can push or pull your case. The handle also locks when fully recessed, greatly reducing the risk of damage when not in use.