What is this jar lid?

[MichaelFla]

That was the vent. The smaller zinc cap would have been marked WGW. That is the lid that has the high value.

 

[dogtx]

Thats neat.
Did you see that it has two hole's on lid it's kind of rough
the glass has no cracks or chips.

 

[DimeS]

That's neat I've never seen one before.