ZEISS 2x Front Lens Attachment 455028 for Zeiss Stemi microscope

  

These front lens attachments for Zeiss Stemi microscopes were rescued from a closing lab. They appear to be in excellent condition, with no visible damage or blemishes. I don't have a compatible microscope to test them, but I see no reason to believe they aren't in like-new working order. They bear the following text.

On the opposite side, they read simply "2,0x". The outer thread on one end of the has an OD of 50 mm, and the inner thread on the other end has an ID of approximately 48.3 mm. Here are some other listings that seem to show the same part.