According to the owner who was selling them on e-bay, they were used as movie props during the filming of the 1995 Stars Fell On Henrietta in the town of Bartlett Texas staring Robert Duval.

I find it amazing or maybe amusing that the prop people found it cheaper to make these insulators than contact one of us - as I am sure most of us have several boxes of common insulators we don't want to throw away - that would be great for kid giveaways, craft projects, or situations like this. --- Rob