It looks like they're belts for an IBM "Executary" dictating machine.
http://www-03.ibm.com/ibm/history/exhibits/vintage/vintage_4506VV4019.html
You have a reference to these things on your own web site:
http://www.richardhess.com/notes/formats/magnetic-media/magnetic-dictation-belts/
John Ross
At 5/2/2007 02:18 PM, you wrote:
A person contacted me today with an approximately 5x8 inch magnetic
sheet with the IBM logo on it and two holes punched in that edge.
It appears to be magnetic material. We have no idea if it's audio
(I haven't seen it before) and I'm suspicious that it MIGHT be a
word processing format. It dates from the late 1960s and was
apparently part of some U.S. Navy documentation.
A photo of it is posted at: http://www.donmarquis.org/ibm.pdf
There are ten of these sheets in the collection.