A 3M sound slide with image slide and sound disc intact. This one has an image of a group of men, possibly 3M staff, clustered around a piece of machinery. A special slide projector would show the slide and play the audio recorded on the dark gray disk simultaneously. They were made by the 3M visual products division Saint Paul, Minnesota in the 1960s.
For more information or to purchase a photograph of this item, view this slide in our collections database.