The Lancer Tactical CNC Piston Head is designed to be used in high FPS builds. Stronger springs put more stress on the piston head as it impacts the cylinder head, which is why high strength aluminum is optimal for high velocity guns. Ball bearings are perfect for alleviating the stress placed on the spring as it cycles. This piston head features a double o-ring design to help ensure the best air seal and compression for a noticeable increase in the AEG’s efficiency.