Collectible?

I have 2 units that I inherited from my father.  They are the Peacock style with PETERSON'S stamped under the Peacock on one side of the cap and made in Japan stamped under the Peacock on the other side.  I first got to use them as a kid back in the 50's and somehow I got the impression that my father had them during WWII.  The Japanese stamp seems to make that improbable.  Anybody know anything about these.  I am going to replace the catalyst and reservoir batting, but not if they should be left original.

I seem to recall that you are correct, in that the Japanese stamp was post-war.

Vintage hand warmers are not something that collectors place on the mantle piece and display like a piece of art. It seems to me that most owners prefer for them to be working, and restore them accordingly.