The invention provides a self-contained cordless electric pool and spa vacuum cleaner which is easily maneuverable over both flat and highly contoured underwater surfaces. A pump impeller, powered by an electric motor, is used to draw water through a compact filter cartridge. The efficiency of the filter...http://www.google.com.tw/patents/US5111129?utm_source=gb-gplus-share專利 US5111129 - Waterproof switch and charging jack assembly
