Seiko's first sports watch, dubbed the Alpinist, debuted in 1959 and was built for outdoor enthusiasts. The Prospex SPB337 Alpinist Black Series limited edition watch channels this classic with modern upgrades. It's powered by an automatic Caliber 6R35 movement, visible through the see-through caseback, housed inside a highly-wearable 39.5mm stainless steel case. Both the case and matching bracelet are given a black hard coating, which is paired with a textured black dial for a stealthy look. Green LumiBrite Pro in the hands and markers increases nighttime legibility, and a magnified date window at 3 o'clock, anti-reflective sapphire crystal, diver-like water resistance, and rotating inner compass ring round out the offering. Limited to 5,500 individually numbered examples.