A transport cage ("cage") and enclosed case combination, wherein the cage is adapted to attach to a vehicle rack where the cage functions simultaneously as a transport container and as a supplemental rack. The cage comprises a first and second tubular framework respectively defining an open box ("box") and a lid. The lid can move between an open and closed position with respect to the box. In the preferred embodiment the cage is designed to accommodate a rifle case. At least one connector enables the cage to be connected to a vehicle rack. The first or second tubular framework enable additional items to be attached to the cage such that the cage acts as a supplemental rack. The cage and case combination is particularly suited to carrying additional items on an ATV rack thereby extending the carrying capacity of an ATV rack.