The WOLFF M&P RP Recoil Calibration Pak is designed for full-size 9mm, .40 S&W, and .357 SIG pistols and includes reduced power springs of 12, 14, and 15 lbs for customization.
These springs require a full-length, non-captive guide rod and come with additional factory weight striker springs for each recoil spring in the pack.
The calibration pack allows users to experiment with different spring weights to optimize their pistol's performance for either lighter loads or to reduce felt recoil for competitive shooting.