Nanbu Tetsubin or cast iron teapots will keep tea hotter for longer because cast iron conducts heat efficiently and distributes heat evenly. These teapots are also durable and wear resistant, so you will not have to worry about replacing them for many years. Japan is the second largest producer of cast iron and these teapots are of high quality, however, with the aging population, there are less and less craftsman available to create these cast iron teapots, and supply is fairly limited. We only carry cast iron teapots made in Japan.