I did not see the one you are talking about, but I have seen a pretty good one at LOZ. It was a blue plastic barrel designed to work horizontally. It had a "cable" from end to end with an eye in the middle, the eye was attached by a cable to a "swing arm" off of the dock with a trailer winch for lifting. The door had a piano hinge on top (I could not tell what the latches were.
Good Luck...