Interesting, thanks for posting.
Thought this may be of interest to while away a few minutes.
https://my.matterport.com/show/?ref=...lp=1&vr=0>=0
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They're for plugging holes in a hull or bulkhead... seriously, it's as simple as that.
Edit: Here you go https://www.force4.co.uk/item/Force-...MaAp8wEALw_wcB