Flip head seat mount replacement doesn’t fit?

Has anyone else ordered the 7x9mm rail replacement head for the endurance vctls seatpost? I got the one on eBay everyone links, for the life of me it doesn’t fit, way too loose where the inserts meet the seatpost. Is there any other option people have been using? The seller told me he’s sold hundreds and never had a problem I can’t be the only one. It’s this one here:

https://www.ebay.com/itm/295745410711?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=fil17m45Q4i&sssrc=4429486&ssuid=wjn-imblt9i&var=&widget_ver=artemis&media=COPY