This one of a kind insulator is simply one of the strangest things to ever enter the insulator hobby.... According to Elton Gish it was found by a bottle digger in the Victor, N.Y area in the late 70's. I just acquired it in trade @ the 2010 Springfield show.
The top design is not strong enough to support much strain in any direction without breaking off the crown loop. these insulators appear to have been intended to suport slack jumper wires in transformer banks, substations etc where some flexibility was needed [id=311252263] Fred Locke made two designs U-339a,u339b. of these "ring insulators" and Pittsburg made at least one . Lima also made them but none have been found to date.
Please see the next three photos for other views of this unusual pin type design [id=295052716].
This insulator was displayed in the Locke display at the 1904 St Louis worlds fare as well as other historic Locke trade displays including a display at a large electric railway trade show in Saratoga Springs, N.Y. in 1903. It can also be seen in a factory photo of a display rack in the the factory electrical test lab engine room from the 1904-06 era.
H ere is a link to the page from the 1903 cataloug showing this unique design [id=461732596] and here is a photo of the piece taken in 1904 [id=295265672] Evidently the production was very limited as only one part of a second specimen was found at the factory, according to long time Locke collector Ken Willick . What evidence we have indicates these insulators were only produced in 1903 and maybe early 1904 in Victor. The glaze and marking on this specimen are from those years.
All of these photos and many more early Locke photos can be seen in Elton Gish's biography of Fred M. Locke available from the author@ http://www.r-infinity.com
Here is a look at the other Locke "loop" design, the U-339B, .[id=265062845]