4 strong polyurethane wheels with stainless steel bearings Retractable extension trolley handle Fold down handles Watertight, crushproof, and dustproof Open cell core with solid wall design - strong, light weight 3 level Pick N Pluck with convoluted lid foam Easy open double-throw latches Stainless steel padlock protectors Automatic pressure equalization valve - balances interior pressure, keeps water out O-ring seal