I learned about stanhope pens this summer while working at an antique shop. I came across a pen missing its stanhope lens which was too bad because thats the whole appeal of the pen. A stanhope is a tiny picture that is housed behind a lens so when the viewer peers into a tiny hole in a pen (or knives, as above) the picture is magnified. These pocket knives all have stanhopes in them. The photo is from The Stanhope Lens where there is lots of information on them too.