24 of the mount 7 are slightly conically shaped with the bevel being smaller than 7 degrees to achieve self locking the plug in opening 24 and the drive shaft 21 form in combination a fit for firmly clamping the attachment brush 5 upon the handpiece 4 of the toothbrush 1 in another implementation the connecting section of the drive shaft 21 and the plug in opening 24 of the mount 7 are cylindrically shaped the drive shaft 21 and the conformably shaped mount 7 can be of an essentially circular configuration when viewed in cross section accordingly the drive shaft 21 forms an essentially circular cone as a comparison of fig2 and 4 shows the drive shaft 21 and the conformably shaped mount 7 have at their front ends a flattening 15 in the form of two opposite surfaces tapering relative to the longitudinal axis 17 in one implementation the whole sleeve shaped mount 7 in the interior of the coupling member 3 is a two part configuration a first mounting member 11 and a second mounting member 12 are both of an approximately half shell shaped configuration so that the mount 7 resembles a longitudinally slotted sleeve the mount 7 can be centrally split in a plane containing the longitudinal axis 17 but the half shell shaped mounting member 11 can also cover an angle segment of less than 180 u00b0 as fig2 shows the mounting member 11 is formed separately from the coupling member 3 so that it is movable relative to the coupling member 3 by contrast the second half shell shaped mounting member 12 has its end which is on the side closest to the working head 2 integrally formed on the coupling member 3 at the bottom of the inner recess 9 owing.