Abstract: The invention relates to a screwdriver or screwdriver attachment (S) comprising one input and one output end (1 and 2) and a shank (4) located in between the two. The output end has at least three, preferably four, ribs (7) which radiate outwards from a central section (8) located around the axis of rotation (x—x). The ribs (7) on each end side have a face, which is placed at an angle to the axis of rotation, and flanks on the front and back side (13, 14) which run substantially parallel to each other in the area next to the frontal face (11). In this area the flank (13) on the front side is located on a diametrical surface (diameter D—D) in relation to the axis of rotation (x—x), whereby the flanks (13, 14) of adjoining ribs (7) form a groove (9) which runs lengthways and whose root (16) ends in the outer surface of a section of the shank.