It works, and allows access either end of what is essentially a waterproof tube. The attachment straps can be attached at different points but none are ideal for a Tubus Logo rack, being either too far apart or close together for the rack length dimension. Also the straps are long and the free ends x 4 tend to flap about. The relatively narrow top of the Tubus Logo rack means that the retaining hooks are required to be placed around and underneath this pack which makes fixation awkward. But other ‘wider top’ racks would not be affected this way. The elastic on the top would be ok except that the spring loaded retainer to shorten and tension the orange elastic does not grip said elastic, it slips and loosens as a result. Overall it does the job, but a simple dry bag and bungee cord is easier to set up and use, and much less expensive.