For Big Twin 12volt 1936-1969. For faster, easier starting, Mallory's new 12 volt electronic ignition system delivers performance and reliability at an affordable price. This unit is a drop-in for 1936-1969 Big Twin (when using stock heads, no head removal is required). This billet distributor utilizes the Unilite Ignition Module, and a bullet proof, fully adjustable mechanical advance unit. Complete with detailed instructions and wiring harness. Sold each.