sockets shall be of brass
Exodus 26:19-21
And thou shalt make forty sockets of silver under the twenty boards; two sockets under one board for his two tenons, and two sockets under another board for his two tenons.
And for the second side of the tabernacle on the north side there shall be twenty boards:
And their forty sockets of silver; two sockets under one board, and two sockets under another board.
fillets shall be of silver
Exodus 36:38
And the five pillars of it with their hooks: and he overlaid their chapiters and their fillets with gold: but their five sockets were of brass.
Jeremiah 52:21
And concerning the pillars, the height of one pillar was eighteen cubits; and a fillet of twelve cubits did compass it; and the thickness thereof was four fingers: it was hollow.