Plastic airtights, ok thanks Torrey. They can't be taken out and are enclosed in a hard plastic so slabbed was the closest thing I could think of.
Still interesting though as I've not seen any others with just one small chip inside like these.
I have some Maxim's plaques that are encased in "lucite" (if that's what it is) which are the only similar items I have. Obviously, I'd prefer them not to be encased but haven't managed to find any yet.
Hope all is well, take care.