UFC CNC Machined Ventilated Concave Alunimum Piston Head for Airsoft AEG Gearboxes (Color: Blue)

"I bought this to replace my stock plastic one because it had a terrible air seal with this its absolutely perfect. Covering the cylinder head with my thumb i can pull the piston back but its impossible to push forward forward so the ports work perfect. I was was frustrated when installing because the bearing falls apart into 3 pieces and you have to drop them into the back of the piston which can cause them to flip upside down.