ProCharger Impeller Cone Spacer. This is only used on P1SC when upgrading from a straight blade impeller to a JB Performance billet D1/D1SC impeller. This is used to help better center the cone on the impeller. It will be loose fit as the piece cannot be press fit if the unit is serviced and has a stuck impeller.
Not pictured, but also included is a longer impeller cone bolt to support this modification. Please use locktite on this bolt.