The motorized micrometer drive Type 864/2 offers excellent displacement characteristics, as required e.g. for inserting glass microelectrodes during intracellular measurement. Together with the control unit (HSE-HA Microdrive Controller Type 864) the Microdrive Type 864/2 represents a complete alternative to previous hydraulic micro controls for the remote operation and vibration-free insertion of the microelectrode into the cell membrane. In addition to the compact construction, a special feature is the backlash-free circulating-ball spindle and the limit switch built into the mechanism. The circulating-ball spindle requires no maintenance and operates virtually without friction, unlike a micrometer spindle with sliding bearing. Freedom from backlash is achieved through the use of factory-selected balls and is maintained through a very long operating life. Absence of sliding friction inside the circulating-ball spindle ensures freedom from the so-called stick-slip effect. As a result the mechanism accurately follows even the slightest displacement settings.