The Omega Speedmaster X-33 was introduced in 1998 as a modern-day Moonwatch - now 'Mars Watch'. As such it featured a high-tech titanium case and an analog/digital movement with a specific set of functions.Reference 3990.50.36 is part of the first generation X-33. It is fitted with a black kevlar strap paired with a folding buckle. The latter sets it apart from the 3990.50.06, which has a pin buckle.