I bought one of these small, sleek units to go w/my new M4 in Germany in 1967. Almost sci-fi looking. It was extremely well-made (at first I thought it was made by Leitz!). It pooped out yrs ago, but does anyone know who made them, please?
You can buy either an Mc or MR meter that will work very nicely with your M4. The MR has a battery-operated meter, the MC is solar cell, using light. At this remove either meter is likely to have issues, either with a dead solar cell (MC) or just iffy electronics (MR, both) but if you look around you can find one that works. They are quite accurate and pretty dependable and, at this remove, not horribly expensive.