From Ascalon Arms:
Increased forced recoil spring for CZ Scorpion EVO 3 and 3+ producing a constant force recoil while maintaining reliable functioning of the weapon.
During the shooting, the behavior of the gun is much more fluent because the bolt impact in the backside of the receiver is damped. This is also relieving the stress from the receiver caused by the bolt impact. The reliable extraction and ejection are maintained by the increased force being situated mainly in the rear portion of the bolt stroke.
The packaging includes nylon cable ties needed for the installation.