PolarStar Airsoft PR-15 V2 Gen3 Fusion Engine Electro-Pneumatic Gearbox Kit (Model: Standard Blue Nozzle)

"I didn't buy mine from this store, but the Fusion Engine is the best thing you can put into your gun. As with any new product you have to tweak it a little bit but once you're happy with the performance you can do anything you want with it. It's a fantastic piece if you're a sniper since it's remarkably quiet when you fire it. And if you're playing a game with single shot only you can feather the trigger and shoot as fast as you want.
The one and only thing that has gone "wrong," is if you take the FCU on and off the wires a lot the wire end they give you can break off, which you can solve with wire strippers so it's not a bad problem.