T-FINS: Helical Straight strip wounds on the tube are mechanically secured. The tubes are a required grade of steel, the fins are aluminum for the maximum tube-wall temperature of 121 deg C (250 deg F) and mild service situations.

H- FINS: H-economizer two rectangular fins, similar to a sq., its edge length for the fluorescent tubes of 2-fold, an enlargement of the heating coil floor. H-economizer flashes resistance welding processes used, the welding seam after the high charge of fusion, weld tensile strength, and has good thermal conductivity.