For the retrofit of old Märklin all-current motors you need a permanent magnet. It replaces the present field  winding, and in combination with a LokSound – or LokPilot decoder, helps to make your loco run astonishingly smooth. We offer 4 different magnets, depending on the particular armature. You find the armature code number on a spare-parts sheet, which you can download from www.maerklin.de.