Available in 8 to 14 inch diameters, there are a variety of different types of woks which all serve various purposes. Although the long or short handles on woks are often chosen for the type of preparation and heat sources to be used, woks with glass rather than metal lids are selected for ease of viewing ingredients while they cook. Stovetop woks are available for use when prepartion takes place directly over the heat source, such as an electric or gas stovetop, hot coals or a heat plate. Some stovetop woks have special stands for wok designed with a round rather than flat bottom so the pan can be kept in a fixed position when used like a traditional sauté pan. Electric woks are made for ease of use as they provide a more consistent heat temperature with controls that can be set for various temperatures. Porcelain enameled grill woks that are formed into square or round steel bowls with perforated holes are another option for wok cooking when cooking over gas or charcoal grills. The grill woks are most used on metal grills for cooking various ingredients over outdoor grills.