Used in custom applications to reduce the 18mm exhaust sensor thread to 12mm, so late model HDs equipped with 12mm O2 sensors can be used with earlier 18mm sensor exhausts.
Note: Touring models require an additional extension cable, which is available as Plug and Cable Extension Kit 578303.
Fits:> 12-17 Softail, Dyna (with pre-2012 exhaust) ; Other applications were 12mm sensors are used for 18mm holes.
