Well, I've sort of decided on a ripstopper cover with a dryco or coverlast(dryco with name change) drain installed. Leaving pool full and installing a push in pool plug in skimmer. Skimmer would be drained but want to install a gizzmo in empty skimmer basket in case plug fails. Anyway, the orange compensator puzzles me. Is it a rubber stopper you push down into skimmer ? My skimmer has threads and looks like it would accommedate a threaded gizzmo better. Also, what is the add on compensator on top for. Do all these gizzmos need to be above water line on top ? I was leaning toward a mesh type cover earlier but this seems to be the best of both worlds in my limited experience. Thanks in advance for any help or correction.