It looks like they're belts for an IBM "Executary" dictating machine.
You have a reference to these things on your own web site:
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.