Strong polyurethane wheels with stainless steel bearings Watertight, crushproof, and dustproof 4 level Pick N Pluck with convoluted lid foam Automatic Pressure Equalization Valve - balances interior pressure, keeps water out Easy open Double Throw latches Fold down handles O-ring seal Open cell core with solid wall design - strong, light weight Retractable extension handle Stainless steel hardware and padlock protectors