Twin Power™ advance unit screw precisely replaces H-D 3570, securing the timer assembly for accurate ignition timing on 1970-early 1979 FL/FX Big Twins and 1971-1979 XL Sportsters.

• Direct OEM replacement ensures stable advance mechanism operation during distributor service
• High-quality steel construction resists vibration and wear in Shovelhead-era engines
• Essential hardware for complete ignition rebuilds or points conversions