PROSTAIR 50 is a technical square used to make the step nonskid and non-slip, protects the ceramic stairs steps preventing from accidents. It is made up of a rigid ALUMINIUM base equipped with a particular toothing on the vertical stem which strengthens the anchorage of the adhesive/tile to the square. The aluminium base varies according to the thickness of the tile used in the step, and to a lined interchangeable insert in vinyl rubber available in several colors. The insert is already applied to the aluminium base. It is compulsory in public places in compliance with EEC norms and prevents from accidents.