Practice
Hard technique
Naked Triple
Three cells in a unit whose candidates come from the same three digits hold those digits. Rule them out of the rest of the unit.
1FocusOnly what mattersNext
Start2Notes givenFull grid, notes filled inLocked
3Your own notesFull grid, you make the notesLocked
4Against the clockHow many in a row?Locked
5 right in a row passes a level