There are 25 posts total. At bottoms are 12x12cm cement pours of varying height, coming up to bottom rails every time. The variation seems due to ground slope and getting relatively straight rails with a near equal distance off ground at one spot or more.

It looks like pours were made right into the hollow plastic posts. The fit looks tight. The hollow rails slide into holes above the pours. If you leaned on this fence, the plastic would break. Garbage.