Vintage dust cover for Monroe mechanical adding machine calculator - $30 (Ames)

Vintage vinyl dust cover for an old Monroe mechanical adding machine.
Probably from the 50s or 60s is my guess.
Could possibly be late 40s.
It's in very great shape for its age.
No stains or discoloration.
The plastic is still very flexible and hasn't gotten brittle at all.
There are a few very small holes and a couple areas where the stitching has become frayed.
See pictures for examples.
It's not perfect, but compared to other examples I've seen online, this cover is in exceptional condition.