Albert Barnes Commentary 2 Kings 25:16

"The two pillars, the one sea, and the bases, which Solomon had made for the house of Jehovah, the brass of all these vessels was without weight." — 2 Kings 25:16 (ASV)

Without weight - The Babylonians did not take the trouble to weigh the bronze as they did the gold and silver. In the Assyrian monuments, there are representations of weighing captured articles of gold and silver in the presence of royal scribes.