This 2DOF (degree of freedom) leg design uses a mechanical advantage arrangement to maximize the payload while minimizing the current draw. It's popular with Hexapod and Quadrapod robot builders. The laser-cut PVC structural components make for a rugged, yet lightweight leg assembly. Made from the highest quality aluminum alloy. All required hardware is included. Ball bearing to attach leg to chassis included in chassis kits, not leg kits. The included brackets are black anodized aluminum.