It has become apparent that the dimensions of inbuilt-collar driving means of the same nominal size may vary according to the method of manufacture. The dimensions of the collar must therefore be adapted to suit the mode of manufacture, at the expense of its strength or mass. Moreover, the transmissible torque for tightening and loosening operations varies according to a useful wrenching height. In order to have a useful height identical to the height of the shank (7), the idea underlying the invention involves pushing the frustoconical collar (152) of a driving means (151) in towards its center along the extension of the sides of the shank. The inbuilt-collar driving means proposed by the invention is suited to all modes of manufacture, and can be manufactured without adversely affecting the dimensions of the driving means or its installation.