A T-shaped seal is disclosed for installation in the gap between a scale pit wall and a scale platform to prevent entry of foreign matter into the area below the platform. An upright stem of the seal is provided on its sides with vertically spaced ribs which may flex during installation between the scale pit wall and the platform edge. The ribs prevent upward dislodgement of the seal against all but intentional efforts and provide additional barriers to foreign material. The stem is of a flexible nature to accomodate irregular pit wall and scale surfaces. A ventilator is shown for installation within an opening formed in the flange portion of the seal and serves to permit the circulation of air beneath the platform while preventing the entry of material into the gap between the scale platform and pit wall.