D.R.P Innen - Liner?? What is this?

[Danger]

Hi Guys,

I saw this today and the person selling it is saying it's German WWII.
He said it's a liner, but for what?

Does anyone know what it is? Is it WWII?

Thanks in advance.

Cheers,

Danger

[BlackCat1982]

No idea what it is, but having a Deutsches Reich Patent number doesn't make it military..