The fin strip is shaped into an L and wound onto the tube surface under tension. Advantages: Core tube extensively protected against corrosion by the fin foot, finning of very thin-walled tubes possible.

Material Combinations:
- Core Tube: Carbon steels low-alloy steels, stainless steels, brass, copper, copper-nickel alloys, aluminum bronze, nickel-alloys (Alloy 400 ext.), bimetal, titanium, and others
- L Fin Tube Fins: Aluminium, Copper

Manufacturing Process:
The manufacturing strip is folded from an L shape and then wound around the base tube. The feet of the fins are joined together and cover the whole of the finned surface. Both ends are clamped down to avoid unrolling through damage.