The L type fin is commonly known as L fin. This finned tube is basically identical to the Wrap-On fin and produced with a combination of Wrap-On and Embedded.The fins are manufactured from strip which is preformed into an accurately controlled L shape similar to the L type, rolled into a taper which causes it to curl. It is then continuously helically wound under tension onto the tube. The fin hugs the tube. The base tube is knurled by a rotating tool, then the foot of the fin is knurled into the knurling of the base tube providing a tight bond with increased thermal performance. Providing the correct fin strip is used the foot of one fin butts up against the next fin and there is no gap between the fins. This gives some corrosion protection to the tube. The fins are secured at each end to prevent unwinding in a similar way as L fins. KL -Foot tension wound finned tubes are commonly used in applications with metal Maximum Operating Temperature- up to 320°C (608°F)