Another unique insulator from Russia. The top is the same on both sides, flip it around and it looks the same. No visible markings. Looks like the top part was glaze-welded onto the "double groove" insulator body.

Apparently there was some additional hardware which attached into the two cavities on the top portion.

There were two screws which held a fusible link of wire, which was positioned over the "peak" of teh top.

This insulator appears to be identical to a Cmielow fuse holder from Poland, as shown: [id=262728195]

Height 115 mm (4.5 inches), base diameter 55 mm (2.2 inches).