Enables the original speedo to be retained and work in unison with the Acewell speedo and its additional functions. Connects into the back of the original speedo. Original cable then plugs into the back of the S2 and the 2 pin QC then connects into the Acewell.
The original speedo cable must have an M12 threaded input to match that of the ACE-S2.

Here are some instructions of how to install an ACE-S2 on a Honda XR400M (Motard). The method is the same for most other bikes.