Maximum airline carry on size Strong polyurethane wheels with stainless steel bearings Watertight, crushproof, and dustproof Automatic Pressure Equalization Valve - balances interior pressure, keeps water out Comfortable rubber over-molded top and side handles Easy open Double Throw latches O-ring seal Open cell core with solid wall design - strong, light weight Retractable extension handle Stainless steel hardware and padlock protectors