The name "Speedmaster Professional" is synonymous with the exploration of space and is best known as the first watch worn on the moon, giving them some pretty serious credentials. It is arguable that Omega would probably have stayed in business and been just as popular if the original moon watch was the only model they ever made for the line. But they didn't stop there, and we're glad they didn't. The years following the legendary Apollo mission saw the release of an expanded line of Speedmaster variants, known commonly as the "Mark" Series. Some of these watches were real flops on the market, and others weren't. Regardless of their initial popularity, all are interesting timepieces and have a collector following today. Of these Mark Series Speedmasters, the one we get asked about most frequently is the first successor to the original Professional - the Mark II.