Not sure what the story is on these. Has the "H" on the dome like the common HG next to it. Every one I have ever seen is lighter than typical aqua for an "H" type, the glass and surface has great clarity (unlike the typical "H" type), and the profile is totally different than the "H" type (looks like a shrunken OVG beehive). I found these scattered on railroad lines. I think the NP, mainly, ... but never more than just one here, one ten miles down the line kind of thing. Not much too look at, but a weirdo, just the same. Anyone ever find them en masse ?