CSF 18-23 Subaru Crosstrek / 17-22 Impreza High-Performance All-RadiatorThe 42mm 2 Row aluminum core not only increases the fluid capacity of the radiator, but also improves the cores ability to dissipate heat. CSF's Exclusive B Tube Technology improves heat transfer by approximately 15% over regular oval welded tubes. In addition, the super efficient multi louvered fins maximize airflow through the core for the best possible performance. Efficiency is key in off roading as speeds tend to be lower overall so you end up