Preserving Nazi vehicle pennant

My grandfather bought back a Nazi vehicle pennant after the war, which was passed on to me. It is a fairly standard looking red background, white circle, black swastika affair. My grandmother used to say he took it from a tank, but it seems more likely to me it was from a staff car.

It is still in its original plastic protective casing, with a surrounding red leather edge and stitching, and two metal mounting fixtures. This is now starting to deteriorate, the leather is somewhat tarnished and the stitching has started to come undone.

Anybody have any ideas on the best way to preserve this historical item from any further deterioration? I don't want to sell it, it is part of the family history.

Sorry for no picture, it is stored at my parents place at the moment, so it is not to hand.

 

I have a historical flag—what’s the best way to care for it?

Tips for preserving your family’s textile treasures:
Temperature: Try not to let your fabrics get too hot or too cold. Store them in a closet, not in a basement, attic, or garage.
Air Pollution: Keep dust off your textiles. Don’t put them in a kitchen or near a fireplace.
Light: Store textiles away from direct sunlight.
Insects: Store your textiles away from places bugs live, like kitchens and damp areas. It is important to inspect your stored textiles regularly.hope this helps deadceleb,ray..