Abstract: A receiver body (1) carries a holder shaft as needed and has on one end face an abutment face (4), extending at right angles to the axis of rotation, and a coaxial, conical receiving bore (5). A connection part (14), which is preferably embodied as a tool carrier, likewise has on one end face an abutment face (15, 15'), extending at right angles to the axis of rotation, as well as a coaxial, conical centering stub (16) fitting into the conical receiving bore. In order to assure a high degree of concentric accuracy, even in the event of strong forces exerted laterally upon the connection part, the inner cone (6) surface of the receiving bore (15) has a cone angle that is larger by a predetermined, small difference angle (27) than the outer cone surface (17) of the centering stub (16). This difference angle is such that upon the insertion of the centering stub into the receiving bore, the outer cone comes into engagement with the inner cone surface first in the vicinity of its smallest diameter.