The following text is by Elton Gish from May 1993 CJ- Porcelain Insulator News for this insulator [id=260297063]to see a picture of this insulator.

"I think that it was Ken Stefan who sent me the following drawing several years ago from an AlEE Journal. This piggy-back arrangement, with M-4395 on top, was used at railroad crossings. You may not be able to make out the numbers, but the drawing shows M-4395 with a top skirt diameter of 15" and the bottom insulator has a 17" top skirt. Note that the bottom insulator has a metal cap cemented on the crown, which has an attachment for the pin to support M-4395. I did not get all of the text of the article, but what was included said that this tandem arrangement was used on one 66 kV line. It was apparently designed to withstand voltage surges from lightning, to prevent the insulators from "spilling". There wasn't a problem with puncturing with these large, thick insulators. The electrical surge was the determining factor for insulation, not the normal line voltage. M-4395 evidently found limited use, since few specimens exist." [id=628623996] to see a photo of this insulator assembly recovered by Jeff and I in 2020 The base insulator has been described as M-4700 though does not have a normal tie head. It has a modified head to take a cemented on metal cap. it Is a pin type and does not have an equipment bolt circle pattern on it's top and is part of a dual pin type assembly.