THIS PRODUCT HAS LIMITED AVAILABILITY.  UNITS ARE USED, BUT WORKING AS INTENDED AND MAY HAVE COSMETIC FLAWS.  Nikon SM, SMZ-5, SMZ-6 (61.5 mm) mount type B for stereo microscopes. The old Nikon product number is 76012 and the new number is MMD14000. These mounts are extremely hard to come by with the coarse focus control! The post mount hole is 25mm. The last known list price (2008) was $252.00.