The present invention provides a dimensional measurement probe unit (100) for attachment to a probe head (200) of a localizer (300), comprising: a measurement probe (150) for dimensional measurement of an object (400); a revolute joint (170) integrated into the measurement probe (150); and a probe unit interface (120) for repeated dismountable connection to a probe head (200) wherein the probe unit interface (120) is revolutely connected to the measurement probe (150) by the revolute joint (170).