There is described a metrological instrument for measuring a characteristic of a surface of a workpicce, the instrument comprising a measurement unit and a user-interface unit separate from the measurement unit. The measurement unit has a sensor which follows a measurement path across a surface and means for deriving a signal indicative of a characteristic of the surface as the sensor follows the surface. The user-interface unit has means for providing a user with an indication of a surface characteristic measured by the sensor. The measurement unit and the user-interface unit have communication means for enabling remote communication of information relating to a measurement between the measurement and user-interface units. Preferably, the measurement unit and the user-interface unit can be connected together when not in use in a manner such that the sensor of the measurement unit is protected.