Fits Big Twin 1970 thru 1999 Evolution® and Sportster® 1971 thru 1995,
when using mechanical advance unit part No. 53-245 or 53-244.

53-50 Single Fire Ignition:
Fires each cylinder individually — no power waste.

53-49 Dual Fire Ignition:
Same as stock,fires both plugs simultaneously.
Use our part No. 53-452 coil or equivalent.