I found this along the line that used the 1911-vintage blue-grey VICTOR suspensions. It has the same cap and glaze, but doesn't have the incuse...not enough room on the exposed porcelain. Note the bottom pin, meant to clamp down on a smaller-sized wire. At first, I thought it was a broken suspension, but it isn't. These were used on a single-wire line along a canyon. It was quite a hike up to get this!