Heat Factory USA in Carlsbad has manufactured personal warming products from its Loker Avenue West headquarters since 1980, making it the oldest warmer brand in the outdoor industry. The product line spans air-activated hand warmers, body warmers, battery-powered hand warmer muffs, and heated headwear with embedded warmer pockets — accessories that complement the technical outdoor layering systems at prAna in the Carlsbad Premium Outlets. Heat Factory cuts and sews many of its accessories domestically at the Carlsbad facility, including gloves, mittens, balaclavas, and stadium cushions. A licensing partnership with Mossy Oak produces a line of heated hunting apparel designed for extended cold-weather sits, gear tested in conditions that overlap with the trails at Lake Calavera Hiking Trail east of the city. The flagship Mini Hand Warmer reaches operating temperature within 15 minutes of activation and sustains heat output for up to 10 hours at temperatures between 135°F and 175°F through an iron-powder oxidation reaction sealed inside a non-woven fabric pouch.