The invention relates to a device for the production of multi-layer, co-extruded, tubular pre-forms made from thermoplastic plastic. A co-extrusion head (10) comprises co-axially arranged flow channels (FK1, FK2), each supplied by a single inlet opening (ZF1, ZF2) with a material melt, distributed annularly in a distribution ring (26, 28). The gap width in each distribution ring (26, 28) is greater in the vicinity of the inlet opening (ZF1, ZF2) than the gap width (s2, s6) in the region of the side opposing the inlet opening (ZF1, ZF2). The flow channels (FK1, FK2) are also asymmetric with regard to the gap widths.