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Pretty sure this is the Asssaver. I got two of them. It works well on the gravel bike but not so well on my track bike and not at all on my MTB. It attaches to your seat tube and rests on your brake bridge. The traingle of brake bridge and seat stays is decently sized on my gravel bike but very narrow on the track bike so it can wobble left and right. The MTB has a wishbone and therefore no brake bridge.
Not seen those before. They are very similar
Looks a bit more like the Ass Saver attachment on the seat tube, I think?