this is a device where one component is a member which , without recourse to any tools , can be attached to or removed from a tow - ball that is anchored to or integral with a tow - bar . the member is rigidly located and unable to move in any plane or about any axis when it is engaged with the tow - ball and the remainder of the device . the member has an integral platform that can be used to support and or tow any desired object e . g . bicycles on a rack attached to the platform .