Sawyer hands Kate the mix tape.
A mix tape is a cassette tape on which a mix of various meaningful songs have been recorded. In "Catch-22", Sawyer gave Kate a mix tape that was actually a tape of The Best of Phil Collins that Sawyer stole from Bernard.
Note: There is no actual Phil Collins album called The Best of Phil Collins.
[Kate pushes Sawyer out of her tent and walks away]
[At camp, Kate is washing the back of her neck with water from the trough. Sawyer approaches, and hands her a cassette tape]