It is essential that these are fitted to all uncapped gutter lengths using the brand's own silicone sealant which makes the installation process quick and easy without the need for any special tools. Zinc Gutta stop ends are an extremely efficient tool to keep your drainage system completely watertight and reduce the risk of flooding. Your large box guttering lengths will sit slightly past the end of your roof to capture as much rainwater as possible during wet and windy conditions. The stop end will then form the seal at the end of the length to prevent the water running to the ground.