Not a bad idea, but you could easily make something similar for next to nothing. Off the top of my head I would say either get a piece of black plastic pipe in the right size, or paint a piece of PVC black, or you may be able to just modify 3 black spray can tops to do the job. I am not sure if a spray can top is too big, but just a few ideas of ways to do this yourself. Another option would be to purchase a thick piece of black marine plywood (starboard) and cut that to size.
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