DuraFin® High Finned Tubes have extruded fin heights up to 0.625″ (16mm). Single metal and bi-metallic finned tubes are available.  Bi-metal finned tubes have a separate alloy liner tube inside the extruded fins.  The mono-metal finned tubes have no liner tube with the fins integral with the tube.

DURA-H Mono-Extruded High Finned Tube

DURA-HB Bi-Metal Extruded High Finned Tube