Metal, a bit dusty from storage but theyll clean up fine.
It looks like they would fit into a slot in the car roof and fix with a bolt, each one marked front-left/right etc.
One has some car details stamped inside (See photo)
Thule roof rack feet (BMW?) (Bear Flat, Bath BA24)
Collection Times
State pickup day/time. 'is it available?' =ignored
State pickup day/time. 'is it available?' =ignored