The housing is machined from a billet of 6061-T6 aluminum on a state-of-the-art CNC machine producing exact tolerances. For high rpm stability, a .500" steel shaft is supported by a sealed ball bearing and a long sintered bushing. This shaft also receives a QPQ coating for friction reduction and resistance to corrosion. A precision machined reluctor is attached to the shaft which triggers the magnetic pick-up mounted in the housing. This high output magnetic pick-up is the most accurate way to trigger your ignition. Plus, with no moving parts to wear or adjust, the pick-up is maintenancefree! Just above the pick-up is MSD's adjustable mechanical advance assembly. Must be used with an MSD 6, 7 or 8-series ignition. Customers can save up to $140 off with the new MSD Pro-Billet Ignition Bundles for small-block Chevrolet, big-block Chevrolet, and Ford small-block engines! These packages include Pro-Billet distributor, the new Ultra 6AL ignition box, plus a Blaster 2 coil. Kits also include timing tape for trouble-free installation. A complete ignition upgrade is one click away with MSD Pro-Billet Ignition Bundles! Different springs and stop bushings are supplied so you can tune an advance curve to match your application.