HK LEM Trigger Kit for all USP and USP Compact pistols and all HK45 and HK45 Compact pistols. This universal factory Heckler & Koch LEM kit is complete with all of the parts required for the conversion.Comes with two hammer springs:The longer hammer spring is for all USP, USP Compact and full size HK45.The shorter hammer spring is only for the HK45 Compact.USP LEM and HK45 trigger pull weights:Use the trigger return spring that is already in your gun for light LEM trigger pull, approximately 4-5 lbs.Use the trigger return spring in the kit for the heavier LEM trigger pull, approximately 7 lbs.