Roller-shaped runner of a cross flow turbine which is capable of being flown through radially from the outer side to the inner side and then radially from the inner side to the outer side, and which has the following features: a. a shaft with at least two end discs being arranged on the shaft at the end side and a plurality of interim discs being fixedly arranged between the end discs on the shaft, with the end discs and the interim discs defining radial planes with respect to the shaft, b. the end discs and interim discs each comprise a plurality of radially outwardly arranged slots in which a profiled blade is fastened in a slot each of two end discs and a plurality of interim discs so that the shaft is surrounded by a ring of profiled blades at a radial distance, characterized in that c. the profiled blade runs parallel with respect to the shaft, d. the roller-shaped runner has an outer diameter D and a length L for which 0.08≤D/L≤0.25 applies as well as in that e1. the profiled blade has a sickle-shaped blade cross section (Q 50) in radial direction of the runner which is defined by a blade inner side and a blade outer side, wherein the blade cross section (Q 50) has a maximum thickness (d s) of the profiled blade in the range from 6 mm ≤ d s ≤ 18 mm, preferably 9 mm ≤ d s ≤ 14 mm, and/or in that e2. the profiled blade is fastened in the slots of two end discs and a plurality of interim discs by means of a welding connection between blade and end disc and interim disc, in which a welding seam (S 52) at a concave blade inner side in a range from 5 mm to 20 mm ends before a closed end of the slot and/or in which at a convex blade outer side, a welding seam (S 54) extends over a part of a range from 10% - 60% of a total length of the convex blade outer side. a. a shaft with at least two end discs being arranged on the shaft at the end side and a plurality of interim discs being fixedly arranged between the end discs on the shaft, with the end discs and the interim discs defining radial planes with respect to the shaft, b. the end discs and interim discs each comprise a plurality of radially outwardly arranged slots in which a profiled blade is fastened in a slot each of two end discs and a plurality of interim discs so that the shaft is surrounded by a ring of profiled blades at a radial distance, characterized in that c. the profiled blade runs parallel with respect to the shaft, d. the roller-shaped runner has an outer diameter D and a length L for which 0.08≤D/L≤0.25 applies as well as in that e1. the profiled blade has a sickle-shaped blade cross section (Q 50) in radial direction of the runner which is defined by a blade inner side and a blade outer side, wherein the blade cross section (Q 50) has a maximum thickness (d s) of the profiled blade in the range from 6 mm ≤ d s ≤ 18 mm, preferably 9 mm ≤ d s ≤ 14 mm, and/or in that e2. the profiled blade is fastened in the slots of two end discs and a plurality of interim discs by means of a welding connection between blade and end disc and interim disc, in which a welding seam (S 52) at a concave blade inner side in a range from 5 mm to 20 mm ends before a closed end of the slot and/or in which at a convex blade outer side, a welding seam (S 54) extends over a part of a range from 10% - 60% of a total length of the convex blade outer side.