Our own cylinder head and piston head combination.  Cylinder head is CNC machined from aluminium 6061 and the piston head is CNC machined from POM-H.  These parts will fit a V2 or V3 gearbox. 

Piston Head: 6 vents, thrust bearing, beveled edge to reduce cylinder scratching, 16mm screw, Viton o-ring.
Cylinder Head: Double o-ring with standard sized rubber pad.

Great XT, SHS and ZCI cylinder compatibility.