This cable is the proper diameter and polarity for Korg products, such as the full Volca line or even the Minilogue or Monologue. It works great to reduce the need for wall warts using these synthesizers in combination with a Cioks DC7 or similar.
This can power the Korg Odyssey too, but beware: the Odyssey has a design flaw on the power board, so I would avoid using that with anything other than the Korg wall warts, to avoid invalidating your warranty.