Cooling device for the external cooling of a film tube subjected to internal pressure in the production of blown films of thermoplastic material, comprising: a cooling gas ring (1; 51) comprising a ring housing (2; 52) with a ring nozzle, which is arranged concentrically to a central axis and is open towards the film tube, and at least one inner ring channel (5; 53) extending in circumferential direction about the central axis and being open radially inwards towards the ring nozzle, wherein at least one feed channel for supplying cooling gas is attached to the ring housing (2; 52), the at least one feed channel being connected to the ring channel (5; 53), and wherein the cooling device comprises only one of the feed channel, and the ring housing comprises only one of the feed opening for the introduction of cooling gas into the ring channel wherein the feed channel is connected to the feed opening via a feed connector attached to the ring housing, or wherein the ring housing comprises a plurality of feed openings for introducing cooling gas into the ring channel, each one of the feed openings is connected to one of the feed channels via a feed connector, respectively, wherein the feed connectors are attached to the ring housing, the feed connectors all enter the ring channel in the same direction with regard to the circumferential direction about the central axis, characterized in that the cooling device further comprising at least one flow guiding device comprising fixed and/or adjustable guide elements in the at least one feed channel, wherein the at least one flow guiding device is arranged and designed such that, when a cooling gas flows through the flow guiding device, at least a partial flow of the cooling gas is set in rotation about a flow axis prior to flowing into the ring channel (5; 53). a cooling gas ring (1; 51) comprising a ring housing (2; 52) with a ring nozzle, which is arranged concentrically to a central axis and is open towards the film tube, and at least one inner ring channel (5; 53) extending in circumferential direction about the central axis and being open radially inwards towards the ring nozzle, wherein at least one feed channel for supplying cooling gas is attached to the ring housing (2; 52), the at least one feed channel being connected to the ring channel (5; 53), and wherein the cooling device comprises only one of the feed channel, and the ring housing comprises only one of the feed opening for the introduction of cooling gas into the ring channel wherein the feed channel is connected to the feed opening via a feed connector attached to the ring housing, or wherein the ring housing comprises a plurality of feed openings for introducing cooling gas into the ring channel, each one of the feed openings is connected to one of the feed channels via a feed connector, respectively, wherein the feed connectors are attached to the ring housing, the feed connectors all enter the ring channel in the same direction with regard to the circumferential direction about the central axis, characterized in that the cooling device further comprising at least one flow guiding device comprising fixed and/or adjustable guide elements in the at least one feed channel, wherein the at least one flow guiding device is arranged and designed such that, when a cooling gas flows through the flow guiding device, at least a partial flow of the cooling gas is set in rotation about a flow axis prior to flowing into the ring channel (5; 53).