SP85-SP170 AEG Tune Up Spring
This Guarder AEG Tune Up Spring is amongst the best and most consistent upgrade springs for your AEG electric gun. It is made of high-quality steel which guaranteed to optimize your rifles performance by maintaining a constant spring force throughout its life time. It offers different velocity options depending on the spring force. This spring will help you get the most out of your airsoft gun.
Note that your rifle's power also depends on other factors such as your barrel length and cylinder volume.