Gravel-Excluder-Leaf-Excluders are used to stop dirt and various objects from entering the drain, obstructing the regular runoff of rainwater; to ensure maximum effectiveness, it is recommended that the drain opening be periodically cleaned of any dirt that may be present. They are resistant to deterioration caused by the sun, ozone and other atmospheric or chemical agents normally present. In addition to keeping the drain clean, Gravel-Excluder-Leaf-Excluders are used to contain the gravel used for the ballast of the waterproof membranes. They are simply inserted into the drain connectors and locked onto the centre of the drain with the fastening bars. The perforated grating allows rainwater to drain away quickly. The raw materials used guarantee a long product life as the plastic materials are treated to maintain their mechanical properties.