An apparatus for securing a measuring or display unit on an object. Included is elongated guide element, on which an orientation aid and a holder for the measuring unit or for the display unit are arranged shiftably in the longitudinal direction of the guide element, wherein the orientation aid and the holder are so positionable relative to one another, that the object is held clamped between the orientation aid and the holder or a mounted sensor, and wherein a resilient tensioning apparatus is provided, with which the measuring or display unit is pressable with a defined clamping force onto the object.