Traditional systems use either a cylindrical seat or a rigid cone for centering.
A cylindrical seat always requires some amount of play (i.e. 25 H5 holder / 25 h5 bolt). Play in such a combination may be as large as 18µm.
In a conical fit the cone must be shaped with great care. Otherwise the stage will protrude immediately (if the bolts are too large), or else the play will be the same as in a cylindrical system.

The function of the ZeroClamp zero point clamping system resembles that of a hollow cone shank. In the latter system, the thin-walled cone is deformed as it is drawn in until its plane fits the contours of the seat.

In principle, a zero point clamping system works in a similar way:
While the cone is being drawn in, the seat ring will be widened minimally. Within the stage or the workpiece in contact with the plane seat, there can be no play.