Treads made of pressure-locked grating, with bearing bars 25/3 mm or 30/3 or 40/3 mm cross flat bars 10/3 mm and pitch 33x33 mm, 33x11 mm and 50x11 mm, special side plates 70/3 mm with eyelets (to be screwed on the stair stringers) and anti-skid profile, hot-dip galvanized as per ISO 1461