Both. It started out years ago as one of those plastic tub child-carrier thingies. I cannibalized parts from it to make a cargo trailer years ago. When I moved to Arkansas I brought the hardware with me, and now I've used them to create a 4' and a 6' trailer so I swap the hardware back and forth. The 6' one is for hauling lumber. The 4' one has since had bungee holes put in, and has been painted - the 6' one is next.