For maximum strength and durability, threaded steel inserts secure the rod ends. The push rods are sold in pairs, fully assembled and ready to install with rod ends and hollow balls. The parts are a direct fit when used with Slayer’s included P2 rockers. For use with P3 rockers (not included), spacers are required; use item #5133 (red-anodized) or 5133A (blue-anodized).