Abstract: There is disclosed in the present application apparatus for continuously measuring a dimension such as the gage of a strand on the thickness of a web by a plurality of reflections of light focused on points at varying distances from the normal center line of the path of the strand or web. The light is conveyed to the various points of a set from a common light source through fibrous light guides and if reflected by the strand or web at a specific point, the light is conveyed to a display board through a light guide of a second set to indicate the size of the strand or web.