A Finned X-Wing is an X-Wing pattern that has one or more extra candidates in one of the 4 boxes. Like regular fish, it is a single-digit solving technique.
How it works
Here is an example of a Finned X-Wing:
The four cells marked X would be an X-Wing if the candidate in the cell marked F were not present. So either there is an X-Wing, or the candidate in F is true. In both cases, the starred cells cannot contain a candidate for this digit. We can eliminate those candidates.
The F cell is known as the fin.
The "/" cells can not contain the "X" candidate.
See Also
