A hammer-shaped soldering bit (hammer bit) weighing 1.1 lb (500 g) but min. 3/4 lb (350 g) is recommended. Its weight guarantees optimum heat storage without overheating. A wide supporting surface (hammer edge) guarantees quick and even heat transfer to the soldering area (the entire overlap area). This is an important feature, as the solder will only flow to areas where there is sufficient heat.