Firstly eBay, sort your rating descriptions.
4 stars is good but with caveats.
The ignition barrel seems decent quality. They weight, switch operation and key operation into the barrel is all good enough.
The size of the barrel is 52mm depth and the thread diameter for mounting is a minimum 18.8mm.
The terminals are screw fittings for eye connectors. I think screws are M4.
There are 3 terminals on the rear; 1 input and 2 output.
There are 3 key positions.
Central position; all off and key removable.
Key to left, one circuit on and key not removable.
Key to right, both circuits on and key not removable.
This vital information should be in the listing.
I should not have had to take a chance and work it out and post this info in a review.
This issue seems ever more common. This site model is built around minimum effort selling and allows diligent work to be exploited.
In this case, Bike It did not supply this information for the vendor to use (who did try to help).
It is overdue being realised, the value a detailed technical description adds value to a product and those without are simply items peddled for maximum profit.