Abstract: A device to code a machine tool holder, to preset the tool length, to mount the tool in the holder, and to inspect tool dimensions and coding. These functions are performed by a ring selector which selects different outside diameter rings in such sequence that a desired indentification of a tool by a combination of lands and grooves is accomplished, by a power torque machine which tightens the tool holder collet, by a digital height and diameter gage device which inspects the tool dimensions, and by a digital ring counter which gives a digital readout of the land and groove combination on the external surface of a tool holder.