Blox Racing BXAC-00600-PO Polished Manual Boost Controller Features a boost dial that is easy to adjust yet will not slip causing over boost conditions Features a lightweight ceramic ball that is more sensitive and reacts quicker during boost operation Includes two additional pressure springs that can be changed for different requirements The light spring is ideal for lower boost requirements and when fine control of boost pressure levels is required The heavy-duty spring is ideal for high boost pressure requirements