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Introduced in 1988, the Speedmaster Reduced was sold as the smaller and cheaper version of the Speedy...
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The most common Speedmaster Reduced models are the no-date stainless steel ones with black dials and black bezels. The first generation included the references ST.175.0032 (leather strap) and ST.375.0032 (steel bracelet). Because Omega changed their coding system in the late 1980s, this version of the Speedmaster Reduced is also known as the ref. 3510.50.00.
In 2006, Omega introduced the upgraded Speedmaster Reduced (ref. 3539.50.00) with a sapphire crystal instead of a Hesalite crystal and a slightly redesign dial. However by 2009, Omega had stopped producing the Speedmaster Reduced collection altogether...
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My favourite of the black dial versions is the 3539.50.00 with a sapphire crystal and no numerals.