ACTION ARMY AAP-01 CNC UPGRADE HOP UNIT by Action Army

Ultimate precision quality at a price that is impossible to beat.

Fantastic quality! Superior high precision hop chamber replacement - you won't get better than this.

Please note, this is for the upgrade hop unit only, the upgrade precision inner barrels are separate and can be purchased separately. 

You do not need an upgrade barrel to use the hop unit, it works perfectly well with the original or pretty much any other brand of inner barrel.