Aluminium New Bore-up piston head (unlike plastic) for maximum durability. Low weight provides good rate of fire and shooting range. Six air channels at the front of the head conduct compressed air under the O-ring. This cause better sealing . 

Axial bearing provide smooth rotation of the compressed spring and aluminium washer provide great durability and cannot crack as a plastic one. 

Package include piston head, O-ring, aluminium washer, screw and axial bearing.

This is NBU (New Bore Up) version and can be used only with the proper larger cylinder!