This "protective plate", as per Mercedes, was marketed to W123's sold in more rugged or less developed areas of the world. In some countries like Finland and South Africa these skid plates were standard equipment. The rest of the world ordered them as needed but most never knew they existed.
This includes a set of the OEM fasteners for installation. You might need one or two common metric bolts but the specialty Mercedes fasteners are all there.
This skid plate is ideal for bad roads, back roads or just protecting the heck out of your investment from the odd city debris. I've seen tire tools and screwdrivers go right through oil pans.
Mercedes quit making this part long ago. This could also be used as a reference for mass production if someone was so inclined.
While this NOS it has the odd marks here and there from storage as shown.
Fun fact: Mercedes is the only automaker that has ever made a line of passenger cars(W123) that include an automatic transmission that can be "roll started" like a manual transmission along with options like skid plates, fender flag mounts, airbags and anti-lock brakes.