I found this at a flea market. It is a dirt-common, brown porcelain, radio-treated, cable-top, triple petticoat ITC insulator (I don't know U #'s), but this one has a rubberized plastic collar type attachment like I've not seen before. Have you? As can be seen in the following photos [id=377542876] and [id=377542974], the collar is quite flexible, and each "cross piece" has a different embossing. The outermost reads: SIDE POSITION LARGE WIRE. The middle one says: SIDE POSITION SMALL WIRE. And the broken, innermost section reads: TOP POSITION ALL SIZES. Finally, there is embossed on the outside side flap beyond this last, broken cross piece: SYNTHETIC PROD. MFG. CORP./PART NO S-825/PATENTED /F-NECK, and next to that there is a 7 and a 3 in tiny circle slugs that appear to be mold numbers. The collar is cemented to the insulator at the heavier section in the wire groove shown in the side view photo. Although the rubber-like material is flexible, there does not appear to be much elasticity to it—it doesn't really "stretch," so I'm guessing it was molded or possibly heat-shrunk in place. Has anyone seen this before? Do you know what it was used for?

Answer: Apparently, this is a rubber snap-on wire tie as shown by David Robbins [id=378588652] and [id=378588791]. Thanks, David. For the life of me, I can't figure out how they get the thing onto the neck of the insulator in the first instance, unless it's molded or shrunk into place. (?)