'Bars' in the Bible

Also he built Bethhoron the upper, and Bethhoron the nether, fenced cities, with walls, gates, and bars;

Therefore he said unto Judah, Let us build these cities, and make about them walls, and towers, gates, and bars, while the land is yet before us; because we have sought the LORD our God, we have sought him, and he hath given us rest on every side. So they built and prospered.