ZUCA Bag Caution Insert & Black Frame w/ Flashing Wheels Inspired by aerospace technology, the aluminum alloy frame is light, super strong and rated to safely support up to 300 lbs The removable, hand washable, Insert Bag is made from premium water resistant 600D polyester The dual wheel system climbs stairs and curbs with ease Magneto dynamic 4" polyurethane wheels absorb shock and make for a seriously silent ride This bag DOES NOT meet FAA specifications for carry-on baggage