This insulator is just one of those pieces you gotta see in person to believe. For reasons unknown, this insulator survived Brookfields poor quality control, and it was never even useable! This 121 was poured with a large and very pourous rock in the wiregroove and, while it was still molten, the rock exploded leaving a dollar coin sized bubble in the wiregroove and skirt area, the skirt and mould contained the blowout from the outside but the bubble expanded outwards in the pinhole closing the pinhole about 1/3rd the diameter. The pinhole bubble is right at point of mandrel entry so there is absolutely no way to get this insulator even started onto a pin! The bubble is completely sealed and unbroken and has rock pieces stuck into all surfaces of the bubble walls from when it exploded and cooled. Unbelieveable and most extreme junk in glass bubbly insulator!