Rotation Bearings is a technology that can be researched at the Research Center in Tech Level 3. It costs 200 Food and 100 Ore, and removes the minimum range of Turrets.

Without this technology, enemy units can move inside the minimum range of the player's Turret, and thus damage the Turret without fear of being shot at. This technology removes the minimum range, preventing enemies from using this strategy.

"Normally, Turrets and Fortresses cannot target units that are directly adjacent to them. However, with this Tech Level 3 technology, they no longer have such limitations."
—Manual description