Different springs and stop bushings are supplied so you can tune an advance curve to match your application. Get your Small Block Mopar fired up with billet accuracy and performance. The MSD Black Cap includes 316 Stainless Steel terminals and Race Rotor and underneath you'll find easy access to the adjustable mechanical advance assembly for easy adjustments. This advance is designed for accuracy and strength with TIG-welded weight pins, nylon pads for smooth movement of the weights and a QPQ coating for friction reduction. Supporting the advance assembly is a hardened, polished steel shaft. Two ball bearing guides are used to support the shaft producing incredible stability. Precision paddles of a zinc-plated reluctor pass a maintenance-free magnetic pickup creating a trigger signal that tells the MSD to fire.