I also think they are too large and cumbersome for a U-Boat. I think the description/answer by Dick Martin makes sense. They do have metal sights for quick target acquisition. Unfortunately, the front part of the sight is broken. There is enough left to tell what it is, though. I can see where there was a tag of some sort on the right prizm cover. Unfortunately, that is missing. Apparently, someone removed it. Otherwise they are fully functioning optics. They don't belong to me, they are in the possession of a friend who tells me his father brought them home, but doesn't know the story - if any - behind them. Too bad, might interesting to know how his dad came by them. There's a good chance, he won them in a crap game or loaned someone a few bucks and got them in return.