a pneumatic twist jet or nozzle 3 arranged following a delivery roller pair 2 and with an immediately thereat flow communicating pneumatic guide tube or pipe 4 which opens towards an output or exit roller pair 5 the term 34 pneumatic guide tube 34 as employed herein refers to a tube or the like which guides an air stream or flow under normal aerodynamic conditions that is to say without sudden changes in cross section and with a roughness normal for pneumatic guide tubes for fibers the jet spinning device 1 is arranged downstream from a suitable drafting arrangement or mechanism 6 which does not form part of the invention and which comprises the delivery roller pair 2 this drafting mechanism 6 also comprises an intermediate roller pair 7 provided with guide aprons 7 1 and 7 2 an infeed roller pair 8 provided with a first fiber sliver condensor 10 arranged before or upstream of the infeed roller pair 8 and a second fiber sliver condensor 9 arranged between the intermediate roller pair 7 and the infeed roller pair 8 the drafting mechanism 6 takes up a fiber sliver 11 or the like which passes into the drafting mechanism 6 in the direction of the not particularly referenced arrow and which is drawn or drafted.