The medium lightweight checked bag is sized for trips up to two weeks. Carry-on bags can nest inside the medium for easy storage. Free-Flex zipper technology stretches up to an inch allowing you to squeeze in a few extra outfits. Engineered with an impact-resistant polycarbonate exterior, tamper-proof double-coil outer zippers, virtually silent spinner wheels, an integrated TSA-approved combination lock and an antimicrobial interior lining.