High quality bearing piston head. It is made of plasti. It is perfect for power tune ups of the replica. The materials used in the production guaranty a long and troublefree operation of the whole system. The application of the bearings prevents the spring from clustering and, what is followed by it, allows to keep a stable muzzle velocity for a longer period of use.The application of the Super Oing type sealing ensures proper sealing and durability of the whole system.