Sturdy polyurethane wheels with stainless steel bearings Waterproof, impact-proof and dust-tight Open-cell core with solid wall structure – robust, lightweight 3-level Pick N Pluck® with open-cell foam Retractable extendable handle, Easy-open two-way latches Folding handles Stainless steel lock frame and protectors Automatic pressure equalisation valve – balances internal pressure and prevents water from entering O-ring seal