Hard to find, brass adapter. With milled slots to code and adapt your screwmount/m39/LTM lenses for the Leica M8.
This one brings up the 28/90 framelines.
Currently coded for the 28mm Summicron, you can fill in the recessed holes as you like.
These were $150 new when he was making them.
$100 PayPal and shipped CONUS.