Large vintage Linhof Heavy Duty Deluxe tripod ball head for use with Heavy Duty Studio and Twin Shank tripods. Would also work with any heavy duty tripod of other make like Tiltall or Bogen. The top plate is reversible with a 3/8" mounting stud on one side and a 1/4-20 stud on the other side. There is a 1/4-20 adapter in the the 3/8 tripod mount on the bottom. 

The lock is nice and tight and the head works well. It shows some wear from normal use but nothing to prevent usage. The top plate is 75mm in diameter as is the bottom. This would be appropriate for medium format or large format cameras as well as modern digital or 35mm cameras.

I have no idea what model or part number this is. For a German factory they are remarkably skimpy on information on their products.