Hidden Triple

Hard Used by Smart Hint

Three heights only fit in the same three cells of a row or column — strip those cells down to just those three.

Cells that establish the pattern
Where the conclusion lands
Height ruled out

How it works

Track heights 3, 4 and 5 across this row. None of them fits in either of the first two cells.
So all three are confined to the last three cells — three heights, three cells, one each.
Those cells can therefore hold nothing else: strike the stray 1s and the 2.
Notice what this did NOT do: it didn't say which of the three gets the 3. Hidden subsets tidy a line up so the next technique can finish it.