The London Fog Brentwood Iii 31"" expandable spinner is a durable polycarbonate construction. There are color coordinating corner guards for added protection. The 8 recessed spinner wheels have control track self aligning technology. Flush mounted transportation security administration (Tsa) approved combination locks on all sizes. The locking trolley handle has aluminum channel tubes for added strength. Interior has a wet pocket, zippered accessory pocket and elastic straps to keep your belongings organized. Thermoplastic rubber (Tpr) cushion grip top and side carry handle and a bottom grip handle make lifting easy. The spinners expand 2"" for additional packing capacity with industrial self repairing nylon zippers.