Guarder SP85 AEG Tune Up Spring

The Guarder SP85 AEG Tune Up Spring is specially designed for AEG (Electric) airsoft replicas and can serve as an upgrade compared to the standard spring.

We regularly get the question which spring provides which fps / joule is very difficult to estimate because it depends not only on the spring what this value will be after placing the spring. The air seal of the cylinder, piston and piston head also have a large share in this.