Compensator for reduced recoil. May require fitting. Fits P9 and CW9 only. ****NOTE: These barrels will not fit older P9 framed models that have not been updated. This update service is available through the service department at a cost of $190 + $25 s&h....If you are unsure of the age of your P9, or wish to have this service performed, please contact the Gun Tech. Support & Service / Repair department.