This 2" (51 mm) Diameter 180 Degree Round Mall Front Clamp attaches with two flat head Phillips screws (included). Suggested minimum gap between tempered glass panels is 7/32" (5.6 mm). It joins vertical glass wall panels set at right angles and provides rigidity to reduce flexing when pressure is applied. They also serve as floating indicators to alert pedestrians of a panel's presence in dimly lit areas.