http://www.ebay.com/itm/252808448756
What you have is an M42 extension tube, 15mm long.
On the outside is a 52mm female filter thread
52mm tubes fit, as do "Cokin" or "T7" type adapters to allow mounting of/to macro stands, ring or other flash, etc.
The inside of the M42 male thread takes a Thorlabs TTL200 or ITL200 tube lens, or Nikon MXA20696 tube or "second" lens. The Thorlabs version fits either way round.
If you need a "52mm tube with M42 inside" then you can fit a 52mm to M42 female on the M42 male end of it.
