In a small space, a cartridge heater produces focused heat. Typically, these heaters are used to heat metal items. Cartridge heaters are manufactured smaller than their nominal diameter for ease of installation. They are, however, available in a variety of tiny sizes, as well as low-watt and high-watt density variants. For packaging, heat sealing, laminating, refrigeration, and hot-melt reservoirs or nozzles, choose a low-watt density cartridge heater. Plastic extruders, hot stamping, medical equipment, food processing, hot-runner molds, and other plastic molding equipment all employ high-watt density cartridge heaters.