Ricardo Beverly Hills Roxbury 2.0 21-Inch 4 Wheel Wheelaboard, Brushed Silver, One Size Corner armor provides added protection at critical stress points. Dual spinner wheel system allows 360 Degree mobility whether you push, pull or walk alongside the case. Cases expand with the pull of a zipper for added packing capacity. A retractable Add-a Bag strap allows you to attach a second bag for easier transport. Built in TSA compliant combination lock safeguards you belongings. "Split book" style opening offers two separate compartments for maximized organization.