I went to one of this seller's pages:https://www.ebay.com/itm/1892-1896-...AOSwZV5c329y
to look at this:
and this box popped up:
This box seems to appear with every one of this seller's items.
I haven't seen this before. Have you?
p.s. Must be a Google-Chrome-only type of thing. Works ok with Internet Explorer and Edge. Huh.