Various materials and systems are available for sealing flat or pitched roofs. The majority of the materials processed to this end around the world consist of plastic geomembranes (PVC and TPO) or modified bitumen. The individual sheets are usually laid so that they overlap. Leister has the right tools for welding all these materials. Alongside welding machines, a variety of hand welding tools with matching nozzles and devices for testing the welding templates are available for details.