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This is the first self-winding watch equipped with Seiko's proprietary “magic lever" system. The magic lever is an innovative self-winding mechanism that uses the simple “claw lever system” efficiently to transmit the power of the oscillating weight in both directions. Magic levers are still used in SEIKO's self-winding watches on the market today. This low-cost mechanism with excellent winding quality instantly dominated the world market, pioneering the popularization of self-winding watches.