“It’s like a magical Mary Poppins bag,” says Dror Benshetrit of his International Expandable Carry-on, part of a new 11-piece collection the acclaimed designer created for Tumi. The patent-pending case is the first zipper-free expandable hard top; its depth can increase from 9 to 14 inches, upping total capacity from 31 liters to 61 (see left). But its creation took a bit more than magic. Benshetrit built roughly 40 prototypes before perfecting the bag’s function, which lets the traveler simply squeeze and lift two interior straps to snap the expansion into place. The real mechanism is hidden: Four sides of sturdy but lightweight thermoplastic expand and retract via a “living hinge” in each corner of the bag’s interior. Similar to the spring mechanism on swinging doors, the hinge extends past 90 degrees. “That was the big step,” Benshetrit says. When the traveler pulls on those interior straps, the hinges retract and the expansion’s frame shrinks inward to then extend vertically; upon release, the hinges bounce back to their original position, securing the expansion. It’s the overpacking enabler.