Abstract: A gauge body with a longitudinal flat bottom adapted to be placed on a surface of one part of a machine; a longitudinal top surface on said gauge body, and a scale element longitudinally adjustably held to said top surface; a guide rail formed along one side of said gauge body and a longitudinal groove along said guide rail; spaced pointer members, each having a pointer body slidably fitting cross-sectionally over said guide rail and in said groove, and a pointer finger projecting from the pointer body over said scale element to indicate the distance adjustment between the pointer members; and a pointer extending over said scale element from another machine part moveable longitudinally relatively to said gauge.