Hi, Good question! I believe it has been salvaged from an old folder that took medium format film or similar. It is thus a large format type lens made for medium format film size.
How to mount it? Scroll down on following link and you can see example how this gent mount such lenses in an old macro bellows http://galactinus.net/vilva/retro/index.html
You can read up more on older lenses on his pages. The rendering of this lens was what caught my eyes, I think it is beautiful, soft beautiful, still reasonably priced.
I should say I do not know how accurate the shutter is. The lens is old, I believe very approximate 1940s or so.