Mr. Kuhar: "It's the top part. The valve section was brown ribbed porcelain about 20-24" long. About 9-12KV, early 1950s H.K.Porter "Crystal Valve" arrester. Around here they had a different top, a porcelain cap & lead in wire."
Mr. Miller: "This is just the top of an old lightning arrester, they made some tops out of Pyrex glass so you could see the brass gaps and tell if the arrester was bad due to burnt gaps."
Photo by Tom Miller, information by Bill Kuhar. Thanks guys!
The glass part: [id=445258216]