Coffee percolators and automatic coffeemakers brew coffee using gravity. The nearby Ruxley factory manufactured kettles and coffee percolators. Percolators were popular until the 1970s, when they were widely replaced by drip coffee makers. There are stove-top percolators and standalone units which contain a built-in heating element. Non-pressure percolators may also be used with paper filters. By the mid-1970s, many companies ceased production of percolators. In 1966 the company introduced "Maxwell House ElectraPerk", developed specifically for electric percolators. Percolators began to be developed from the mid-nineteenth century.