I recently bought at haul and found a bunch of these regular sized bricks. Can anyone identify the for me?
They are 2x4 bricks, but with holes in the side of the bricks:
From: https://i.stack.imgur.com/Atc7p.jpg
It says Lego on the stud, but no part numbers are to be found anywhere, so I guess they are old.
Any help is appreciated.