Founded in 1945, Sub-Zero is a privately held company in its third generation of family ownership. Headquartered in Madison WI, Sub-Zero also operates a manufacturing facility in Goodyear, AZ. Sub-Zero, Inc. is the leading manufacturer of American-made residential luxury refrigeration, freezers and wine storage units and it leads in product design with its built-in and integrated lines. Specializing in food preservation, Sub-Zero pioneered the concept of dual refrigeration and prides itself on being the first company to store frozen foods at ultralow, ''sub-zero'' temperatures. Wolf Appliance is the premier producer of ranges, ovens, cooktops, and grills and was among the first to introduce the convection oven to the residential market.