Pocket magnifier - at least that's what I think this item is and it's untested as I haven't actually used the item - it was included in a box of vintage lenses that I bought some years ago.  It's got a small lens in one end and a pin-hole, both ends unscrew and there's a glass plate in one end.  What I think you do with this is put a suitable small translucent sample on the glass plate, reassemble then hold the pinhole end up to a bright light source and you should see a faint magnified transmitted-light image of the sample.  Comes in a little cardboard tube shown in listing photos.

Interesting vintage pocket-sized magnifier and probably something for a collector, or someone who actually knows what it is!

The item will be well wrapped and shipped by Royal Mail.

Thanks for looking.