The "set screw" type of powder die is the oldest system out there. No, you do not need one. On your powder measure, where the Allen bolt fastens the pivoting arm on, is where the fail safe system will go on. You will replace that arm with a new one and the rod will attach to it. Make sure when you order it, you ask if it will work with your measure. There might need to be some modifications done to make it work. Just ask Dillon, they will know.