The main benefit of washer dryer combination units is their compactness. A matching dryer was introduced to accompany the new washer. Common bolt heads include hex, slotted hex washer, and socket cap. In 1947 it introduced an automatic, spinner-type washer sold by Sears under the "Kenmore" brand. Also, the wiper, window washer and light switches are different. In 2003, Maytag introduced their top-loading Neptune washer. A common application for this style of pump is in a parts washer. This model saw the introduction of an electric window washer pump to improve driver visibility. Some spark plugs have a tapered seat that uses no washer. The fastener serves the functions of both a lock washer and a nut. Methanol poisoning most commonly occurs following the drinking of windshield washer fluid. Alva J. Fisher has been incorrectly credited with the invention of the electric washer. A common use of sodium hydroxide is in the production of parts washer detergents. The bolster spring sits on the rubber washer. A Belleville washer is a type of spring shaped like a washer.