I think it's genuine.
With the cell was the wrong warranty card included, hence the serial didn't match with anything on the box or the cell.
I sent back the cell, and they fixed the rattling, and included the correct warranty card.
This is the reply from the seller.
Our engineer team have asked the supplier to inspect and found that the cell sheet is in normal condition no need to replacement the cell. Which this case, the supplier advise the engineer to adjust the cell sheet placement in the slot to be aligned with the upper lock for better density.
*Since the Tri-large 35g/h cell is longer than the Tri-Compact 25g/h cell and the 18g/h cell, and also has a locking point on the top, there is a chance that the cell sheet may move slightly.
Fluidra, which is the official Zodiac distributor worldwide, already confirmed that the cell was genuine.

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