This Boost Timing Master is made for use with MSD ignitions and enables you to adjust the ignition retard amount from 1° to 3° per pound of boost via a dash-mounted control knob. You can make adjustments on the fly to prevent detonation as fuel quality or altitude and air quality changes up to a maximum of 15° retard. There is a boost pressure port to connect to your manifold and the Boost Timing Master wires easily to the MSD Ignition Control.