Copper Cap?

[stitchlips]

I believe this is copper. It rings up on my CTX 3030 right where copper does. It has a nice green patina. It is very smooth, light, thin but yet very strong. It looks like a cap to something, but what? Anyone seen anything like it?
Thanks in advance.

 

[Elton]

n/t

 

[1859large]

Could it be a lid for a thermos flask? 1950s vintage?

Just a guess.

HH

 

[jajayo]

The item is from a 1930's or 40's flashlight. It held the batteries in the back.

 

[taz42o]

Id say your right.

 

[stitchlips]

That looks like it. Amazing and thanks for the ID!