This Olympus VF-1 Viewfinder is designed for the 17mm Micro Four Thirds pancake lens, so it covers the 35mm field-of-view.
This bright-line optical viewfinder mounts on the hotshoe.
It features multi-coated glass lens element construction.
The image quality is equal to the best German viewfinders, which cost 6x as much.
Brand new, without the box, as I bought it in a camera kit.
$75 + $5 shipping.