added by somebody...to mount something like a table or BBQ...surprised PO did not include it in the sale. It does appear to be a the perfect height for an outside dining table...under cover of the
awning....
check your inside table...maybe the hardware fits the track (???). If it was me, as the screws look blackish, I would remove one of them, source out SS screws and remount the whole thing with a good sealant of your choice....BFs last a LONG TIME, regular screws on the outside rust/become loose.....I've replaced dozens on mine