Citizen Mechanical Watch Collection Open Heart Men's Wristwatch

The Citizen Collection Mechanical Open Heart is a four-model lineup of Japanese-made automatic watches released in August 2026, marking Citizen's latest entry in its core mechanical collection. Built on the Caliber 8229 automatic movement — 21 jewels, ~42-hour power reserve, hand-winding and hacking supported — these watches offer a strong blend of classic and modern design without compromising on finish or character. The defining feature is the open-heart aperture at 7 o'clock, through which the balance wheel can be observed in motion — the literal heartbeat of the watch made visible. The 41mm stainless steel case pairs a slightly wider bezel and lug with mirror-polished cut surfaces on the bezel and beveled bracelet centre links, creating a dynamic interplay of light that changes with every shift of the wrist. The index cut parts are thick for visual presence but thinly finished on the flat plane for a refined, delicate edge. A see-through caseback reveals the movement from behind. Four variants: Silver (NH9150-52A), Black (NH9150-52E), Blue (NH9150-52L), and Silver/Gold Two-Tone (NH9154-51A). Made in Japan.

Key Features:

• Open-Heart Aperture at 7 O'Clock: A window in the dial at the 7 o'clock position puts the balance wheel on full display — the component responsible for regulating the movement's timekeeping, oscillating back and forth up to six times per second. It's mechanical watchmaking made tangible on the wrist.
• Citizen Caliber 8229 — Automatic + Manual Winding, Hacking: The 8229 is a solid everyday automatic caliber: 21 jewels, approximately 42 hours of power reserve on a full wind, manual winding capability, and a hacking seconds hand that stops for accurate time-setting. Mean daily rate of -20 to +40 seconds.
• Mirror-Finished Bezel Cuts & Beveled Bracelet Links: The cut surfaces of the bezel and the angled faces of the bracelet centre links are mirror-polished, creating a sharp contrast against the brushed surfaces and a dynamic appearance that shifts with the light — a finishing detail that punches well above the price point.
• See-Through Caseback: The movement is visible from the rear through a see-through caseback, allowing the full caliber to be appreciated from both front and back.
• 10 Bar Water Resistance & Made in Japan: The 41 x 11.7mm stainless steel case is rated to 100 metres (10 bar) of water resistance — more than sufficient for everyday wear and light water activities. Made in Japan, with a Citizen manufacturer's warranty.

Watch Specifications

Product File
Brand: Citizen
Product: Wristwatch
Movement: Automatic
Display: Analog