What kind of tube is this?

[Mike Caldwell]

Hello
Just wondering if anyone has seen a tube like the one pictured here.
My guess is that is some sort of a display tube, maybe neon in nature as it has no filiment that I can see but it is no where
near as complex as a "nixie" display tube.

In a diamond shaped logo there are the letters GR and the part number 1538-1 there may have been another number after the 1
but I can't make it out.
Under that number is the number 7405.
If any one has any ideas let me know.

Thanks
Mike Caldwell