Tree Grille Steel | Radial DesignTree Grille Steel Radial Design An AUTOPA Radial Tree Grille plays a crucial role in enhancing urban environments. Made from galvanised mild steel and finished with a standard black coating, these grilles protect sensitive roots from damage caused by both vehicular and pedestrian traffic. Their modern design makes them suitable for any location. They are supplied in two sections that are fastened together with bolts. Each grille comes with a frame