Thank you for viewing. 931A HAMAMATSU 1 piece Collection Item The specifications and uses are unknown, and it appears to be an old photomultiplier tube from Hamamatsu Photonics, but please forgive me if it is incorrect. Please check the product name and condition in the photos. The product name was read from the label, but please forgive me if it is incorrect. There is no box. The size is approximately 88mm in length and approximately 33mm in width. A socket is included. (There are traces of soldering and wire cutting.) It looks different from a vacuum tube. Operation has not been confirmed, and due to long-term storage, there is a possibility that it will not operate normally. Please consider it as a collection item or a junk item. There is no guarantee of operation. Therefore, "Collection Item" is included in the product name. If you agree, please purchase.