The P21 dual piston cylinder is a power source device matched with the K50. K51 wedge power chuck. Adopting a dual piston structure, the cylinder structure is compact, with a small volume and high push-pull force, ensuring reliable performance. The main component materials are made of aluminum alloy, which is lightweight, fast to start, and can greatly reduce the load on the tail of the machine tool spindle. The air distribution valve is supported by rolling bearings for easy lubrication.