'Bars' in the Bible

He also built Upper Beth-Horon and Lower Beth-Horon, fortified cities [with] walls, gates, and bars;

And he said to Judah, "Let us build these cities and surround [them with] walls, towers, gates, and bars while the land [is] before us, because we have sought Yahweh our God. We have sought and he has given rest to us on every side." So they built and had success.