An extrusion die having: first and second manifolds (300, 400), converging first and second internal flow passageways (350, 450) extending respectively from said first and second manifolds, a downstream flow channel extending from a convergence of said first and second internal flow passageways (350, 450), an outlet orifice, and an internal deckle system, wherein said internal deckle system having an encapsulation position, a full-width position, and a naked-edge position, said internal deckle system when in said encapsulation position configuring said extrusion die to produce an encapsulated composite extrudate comprising a core layer and a skin layer of greater width than the core layer such that the skin layer defines lateral edges of the composite extrudate, said internal deckle system when in said full-width position configuring said extrusion die to produce a full width composite extrudate comprising a core layer and a skin layer both extending over a full width of the composite extrudate, said internal deckle system when in said naked-edge position configuring said extrusion die to produce a naked edge composite extrudate comprising a skin layer and a core layer of greater width than the skin layer such that the core layer defines lateral edges of the composite extrudate, wherein said internal deckle system comprises a first internal deckle member received in both said first manifold and said first internal flow passageway, a second internal deckle member received in both said second manifold and said second internal flow passageway, characterised in that said internal deckle system further comprises a third internal deckle member received in said downstream flow channel, said extrusion die having a deckle control system comprising a movable deckle carrier to which said first, second, and third internal deckle members are mounted, said first, second and third internal deckle members being conjointly moveable together with said deckle carrier relative to said extrusion die in response to conjoint actuation by said internal deckle control system, said first and second internal deckle members being independently moveable relative to said extrusion die, to said deckle carrier and to each other in response to independent actuation by said internal deckle control system. first and second manifolds (300, 400), converging first and second internal flow passageways (350, 450) extending respectively from said first and second manifolds, a downstream flow channel extending from a convergence of said first and second internal flow passageways (350, 450), an outlet orifice, and an internal deckle system, wherein said internal deckle system having an encapsulation position, a full-width position, and a naked-edge position, said internal deckle system when in said encapsulation position configuring said extrusion die to produce an encapsulated composite extrudate comprising a core layer and a skin layer of greater width than the core layer such that the skin layer defines lateral edges of the composite extrudate, said internal deckle system when in said full-width position configuring said extrusion die to produce a full width composite extrudate comprising a core layer and a skin layer both extending over a full width of the composite extrudate, said internal deckle system when in said naked-edge position configuring said extrusion die to produce a naked edge composite extrudate comprising a skin layer and a core layer of greater width than the skin layer such that the core layer defines lateral edges of the composite extrudate, wherein said internal deckle system comprises a first internal deckle member received in both said first manifold and said first internal flow passageway, a second internal deckle member received in both said second manifold and said second internal flow passageway,