Worker 5kg spring upgrade for Elite Alpha Trooper. This is the best bang of your buck spring upgrade for your Elite Alpha Trooper!
The package includes a 5kg main spring, a better O-ring for the breech, a silicone padding for the plunger tube to protect the Plunger rod from dry firing.
This spring can push a stock Elite Alpha Trooper blaster to 80FPS and more with the Air Restrictor in. I have personally tuned a Elite Alpha Trooper with this spring and it can do more than 90fps easy. You may wonder, why only 5kg? This is due to the design limitation of Elite Alpha Trooper that uses a very thin priming rod for the prime action, if you use more than 5kg spring, the prime rod will bent and worn out prematurely.
PS: FPS chrono test is done with Hasbro Elite Dart.