Here is the new line of Seves-Sediver suspension insulators. Note the Outerib style. I believe this is a new style believed to be better in the fog.
Shown in the photograph are a Standard profile, Fog type profile, Spherical profile, Open profile and Outerib (Outer rib?) profile suspension insulators.
The picture is from a high resolution version of a photo (which was emailed to me) in one of their on-catalogs .
Photo courtesy of Seves-Sediver and used with permission.