This porcelain "portafusibile" fuse holder shows its electrical and mounting hardware. Similar size as the CD 650 glass MIVA T5S, manufacturer unkown, probably Richard Ginori or Verbano. Dimensions are 8 cm tall, 6 cm base diameter. The "fuse" is simply a few strands of thin wire connected between the two "eyes" and held in place with the thumb-screws.

I imagine that replacing a blown link could be somewhat "exciting", if there was no upstream power cut-off available...

A similar photo is posted over at "porcelain insulators".