It’s no mystery why the Citizen Ref. 4-600851 Y Challenge Diver has earned its cult following: It's got rugged good looks, classic dive watch charm, and the kind of toughness that laughs in the face of danger. With a 40mm stainless steel case and 20mm lugs, it strikes that perfect sweet spot: Bold on the wrist, but never bulky.
 
While Seiko was busy experimenting with fancy (and ultimately flawed) locking crowns on the 6105-8110, Citizen kept it real with a no-nonsense screw-down system" Simple, effective, and reliable. Though like with many vintage divers, the crown tube is part of the case, so you'll want to treat it with a bit of respect. 
 
Under the hood, you’ll find Citizen’s trusty 21-jewel Caliber 6000 automatic movement, humming along at 21,600 beats per hour. Bonus points: It’s hand-windable and even packs a quick-set date function, something many fancy Swiss brands didn’t catch onto until years later.
 
And let’s talk about the style. The vivid green lume? Glorious. The red date wheel? Chef’s kiss. Sure, the deep-set crystal doesn’t have a magnifier, so the date might be a little shy at first glance, but who’s rushing when you’re wearing something this cool?
 
The best part? This particular example is straight out of a time machine: New old stock condition, rocking its original and still soft Tropic straps, signed Citizen buckle, and original price tag. Even the protective film is still clinging onto the case back like it's 1975 all over again.
Bottom line: it doesn’t get better than this.
 
The watch currently works flawlessly and will be sold as is. Please let us know if you wish to service it.
 
Ships from Tokyo, Japan