Seiko Prospex Automatic GMT Men's 42mm Watch HBC001J

The Seiko Prospex HBC001J is a modern reinterpretation of Seiko's 1968 heritage dive watch, now upgraded with a mechanical GMT complication for tracking a second time zone. It's powered by the in-house Calibre 6R54 automatic movement, delivering a 72-hour (3-day) power reserve — among the longest of any mechanical watch in its class. The 42.0mm stainless steel case is treated with a super-hard coating and finished with mirror-polished case sides that reflect its heritage design. A green ceramic unidirectional rotating bezel with a knurled edge sits atop the case, paired with a flat sapphire crystal featuring an anti-reflective coating on the inner surface. The dark green dial carries a textured finish, with oversized hour markers and hands heavily coated in LumiBrite for legibility in low light or underwater. A gold-tone 24-hour GMT hand tracks the second time zone independently of the main hands, and a date window sits discreetly between the 4 and 5 o'clock positions. The watch is fitted with a stainless steel bracelet and Seiko's redesigned tool-free slide-adjuster clasp, adjustable in six steps of 2.5mm for a total range of 15mm — ideal for accommodating wrist size changes during diving or daily wear. It's water resistant to 300m.