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Two cells in the same row, column, or box that each have exactly the same two candidates left. Between them they must use up both digits, so no other cell in that house can hold either one.
A subset technique: two cells whose candidate lists are identical and contain only two digits.
Look for two cells sharing a house where each has exactly two candidates, and those two candidate lists are the same.
Those two digits have to fill those two cells in some order - there's no third cell in the house available to take either digit.
R2C3 and R2C7 both have only {2, 8} left as candidates. Whichever way those two digits split between them, no other cell in row 2 can be a 2 or an 8 - eliminate both from the rest of row 2.
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