What is that?

[dalex100]

Well, my father just gave this to me yesterday! I was wondering what could I do with it. I just see that it makes "multiple pictures". Anyone know?

 

[dxqcanada2 1]

Back in the old days ... special effect filters where everywhere (before Photoshop).
These prism filters were one of the dumbest. Usually used for portraits to get that triple headshot look.
Like this example I found on the web: Britanie | Flickr - Photo Sharing!