I dont collect these, but found one buried in mud. I'll attach a pic if anyone is interested. I was wondering where these date in the world of insulators. Brief desc: Round...has a cable notch running across the top.
Early to mid 1900s power (High Voltage) piece made by the millions and about worthless in collector terms. Still, it's better to find one of those than a rock.
Well I picked it up along with many a broken applied lip tops (mostly flasks) that day. It was nice to see something whole! Have to take the bad with the good I guess.
It can be tough to tell with a dark glaze like that, but does it have any markings at all? As Jim said, it's not valuable in collector terms but it's certainly a nice find. It's hard to argue with "free."