Jonathan,

Those are the ones --- Tuff Bins. We also put two of them on our ARC22 trailer. We cut a 6 inch long section of 4" diameter, sch 40 aluminum pipe in half, hetaed it up and closed it some in a vise, then through bolted one each on top of the boxes' lids, added some indoor/outdoor carpet inside the coupling and that is where we carry our cat trax. The boxes' lids carry the weight with no problem.

Good luck shopping.

Don