At first glance, this insulator appears to be a CD 160.4. It is 2 3/4 inches across and 3 3/4 inches tall and the profile matches that of the price guide on page 208. It has no embossing other than what could be a small 1 on the base. It could be a stray mark but it does have the flat horizontal base and serif on top. The base is otherwise well formed and smooth. However, it has no inner skirt so therefore one would conclude it is a CD 134. It has Pennycuick threads with a very defined cone shaped point on top of the pinhole. The pinhole is also out of round looking like an oval. It has a 1/2 inch vertical bar on the inner skirt. I have seen many pictures of CD 134 Pennycuicks in the ICON photo gallery and the wire groove on this one is completely different. The profile looks more like a CD 134 American or Oakman. On top of all of that, the skirt is slightly concave and is widest at the lower wire groove. The base is actually slightly narrower. Has anyone else encountered a piece quite like this one?