FTP introduces the all new M113K 55K AMG Adjustable ring Crank Pulley Kit. With interchangeable boost rings, you will never need to uninstall your harmonic balancer again!! if you want more power, Just swap out the outer ring to another Size. This Pulley kit is Harmonically dampened just like the OEM MB Crank Pulley, and Offers many added benefits over the Welded Ring Design of the older style ASP Pulleys.