Proto Matrix, Freak Barrel, 68/4.5k pmi HPA, CP Roller Trigger
-Hard to Install
The CP Roller Trigger is kinda hard to install because you have to line up those bearings with the trigger hole and with the trigger and it moves around alot when you try to put it on and falls off too. It just fits the gun so its hard to put on. But I would say its worth the trouble of putting it on. This thing feels light as hell and there is no resistance like a stock trigger and it even has super fast return even without a spring (which doesn't fit with uncut/stock spring).
Get this thing, for ~$30 this will be one of the best upgrades.