This photo shows a Friction-Stir Welding "Large size" Skive Fin heatsink.
Details same as Skive Fin Heatsinks (small size), different fin thickness, fin pitch, fin height & fin width heatsink can be welded become a large heatsink by Friction-Stir welding method (no extrusion mould is needed, except the aluminium plate size for skiving is not avaiable in mainland China, then we need to open mould for making this special size al. plate).