Naked Pair

Medium Used by Smart Hint

Two cells in a row or column share the exact same two candidate heights — remove those heights from the rest of the line.

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

How it works

The first two cells of this row are down to the same two heights, {1, 3}.
Whichever way round they fall, between them they use up the row's 1 and its 3.
So neither height can appear anywhere else in the row. Strike both from the other two cells.
That happens to settle them here — a 4 and a 2 — but the pair itself is still unresolved. Eliminations first, placements follow.