Prometheus MS90 Non-Linear Spring

The Prometheus MS90 Non-Linear Spring can be perfectly used as an upgrade for your airsoft replica and is of very good quality.

We regularly get the question which spring provides which fps/joule which is very difficult to estimate because it does not only depend on the spring what this value will be after fitting this spring. The airseal of the cylinder, cylinderhead, piston and pistonhead and nozzle, among others, also have a large share in this.