Hi Lo Detector 10ft.  HM-416
Used for measuring pavement planeness.   Operated by one person along a highway, airport runway, or bridge surface.  The unit detects and dye- marks high and low areas that need to be ground or rerolled.  Variations are magnified 16 times on a vertical scale graduated in 1/8" increments up to 1/4".  Uses replaceable bright orange aerosol marking dye.  One case, (12) cans, comes with unit.