https://www.aliexpress.com/store/product/LJXH-Finne-Tubular-Heating-Element-201-Stainless-Steel-Radiator-220V-700W-750W-800W-Drying-Oven-Electric/3242007_32893284834.html
https://www.aliexpress.com/store/product/LJXH-Finned-Tubular-Heater-U-Type-M18x25mm-Connection-Screw-Size-U-Type-Tube-Dia-10-12mm/3242007_32892797232.html
Fin electric heating tubes are more commonly used in printing machine oven electric heating tubes. Printing machine oven electric heating tubes are made by winding fins on the basis of light tube electric heating tubes or wearing square fins.
https://www.aliexpress.com/store/product/LJXH-U-Type-M18-16-Electric-Finned-Tubular-Heat-Pipe-U-shape-Fin-Heating-Element-U/3242007_32890990119.html
https://www.aliexpress.com/store/product/LJXH-W-Type-Electric-Finned-Tubular-Heat-Pipe-M18-16-25-W-shape-Fin-Heating-Element/3242007_32889289915.html