This is the large width housing plug that fits into the bottom of the KD1 manual advance/retard housing, at the base of the cable mechanism, it is often missing from original magnetos - as eventually it could come lose and drop out - which then let dirt and grit in, which can lock up the mechanism.
These are manufactured to the original dimensions and are then plated as per the originals.
They also have the original small hole in the middle - important as it stops damp and condensation forming
Price is each