HANBORO 937 Tonneau Automatic Watch – Miyota 82S7, Carbon Fiber, Rubber Strap, 50M

HANBORO 937 Tonneau Automatic Watch – Miyota 82S7, Carbon Fiber, Rubber Strap, 50M

The HANBORO 937 is a 50mm tonneau-shaped automatic watch built around the Miyota 82S7 — a genuine Japanese movement with a factory open-heart balance wheel window, small seconds subdial, and 24-hour indicator. Carbon fiber bezel with stainless steel case construction. Mineral crystal. Soft rubber strap with butterfly clasp. Luminous hands and indices. Exhibition case back. 14mm thick, 128g, 50M water resistance. Available in red, black, and black/green accent colour variants.

Key Specifications

Miyota 82S7 — Genuine Open-Heart Movement

The Miyota 82S7 is a documented Citizen/Miyota Japanese automatic caliber, part of the established Miyota 8200 movement family. It is factory-designed with a built-in open-heart window at the 7 o’clock position specifically to display the balance wheel — this is not a custom skeleton modification but a feature engineered into the movement itself. The caliber also includes a small seconds subdial (between 4 and 5 o’clock) and a 24-hour indicator (at 9 o’clock), alongside central hour and minute hands.

Specifications: 21 jewels, 21,600 bph, approximately 42-hour power reserve, and a stop-second (hacking) device that halts the seconds hand when the crown is pulled for precise time setting — a feature not present on the more basic Miyota 8215. Accuracy is rated by Miyota at -20 to +40 seconds per day. To fully wind the movement from a depleted state, rotate the crown clockwise approximately 40 times.

This is a meaningfully better-documented movement than several other models in the HANBORO range — the 82S7 is independently verifiable through Miyota’s own technical specifications, giving buyers confidence in long-term serviceability.

Tonneau Sport Case Design

The 937 uses a wide tonneau (rectangular/barrel) case shape rather than a round profile — a design more associated with racing and motorsport-inspired watches. At 50mm in height and 14mm thick, this is a large, substantial watch with significant wrist presence, suited to buyers who want a bold sport mechanical piece.

Carbon Fiber Bezel

The bezel uses a carbon fiber-style textured surface combined with a stainless steel case structure underneath — giving the watch a performance-oriented visual character with exposed side screws reinforcing the technical, racing-inspired aesthetic.

Skeleton Dial Layout

Beyond the movement’s own open-heart window, the dial carries layered bridge details and visible gear elements consistent with a skeleton presentation. Large luminous hands and hour indices are layered over the open mechanical base to maintain legibility despite the busy dial.

Mineral Crystal

The front crystal is mineral glass with anti-scratch treatment — not sapphire. This is a lower-grade crystal material than several other watches in the HANBORO range (which use sapphire mirror crystal), so buyers prioritising scratch resistance should weigh this against the documented movement upgrade.

Rubber Strap and Exhibition Back

Soft rubber strap, 24mm width, with a butterfly clasp closure — suited to casual and sport wear rather than formal dress contexts. The case back is an exhibition window, allowing the automatic rotor and movement to be viewed from the rear in addition to the dial’s open-heart window at the front.

50M Water Resistance

Rated 50M / 5ATM — suitable for splash exposure, rain, handwashing, cold bathing, and swimming. Not rated for snorkelling or diving. Keep the crown closed during water exposure.

Colour Variants

Red — red case and strap combination, the boldest of the three options.

Black — dark carbon-style finish throughout; the most cohesive monochrome racing aesthetic.

Black/green accent — black base with green accent detailing on hands or dial elements.

How the 937 Compares to Other HANBORO Models

The 937 is the only model in the HANBORO range on this site to use a fully documented, independently verifiable named movement (Miyota 82S7) rather than an unnamed proprietary or less-documented caliber. For other HANBORO skeleton and mechanical-statement designs, see the HANBORO 851 Double Flywheel (Shanghai JH515, dual flywheel dial), the HANBORO King Bee Series 2003 (honeycomb skeleton, calendar/24-hour sub-dials), the HANBORO Roulette Automatic Watch (Miyota 8215, spinning roulette wheel), and the HANBORO Sailing Series (3D ship dial dress watch).

FAQ

What movement does the 937 use? The Miyota 82S7 — a genuine Citizen/Miyota Japanese automatic caliber with a factory-built open-heart balance wheel window, small seconds, and 24-hour indicator. 21 jewels, 21,600 bph, approximately 42-hour power reserve, with a stop-second hacking device.

Does the watch hack? Yes — the Miyota 82S7 includes a stop-second device. Pull the crown to the time-setting position and the seconds hand stops, allowing precise synchronisation.

Is the crystal sapphire? No — mineral crystal with anti-scratch treatment. This is a lower-grade material than sapphire; consider this if scratch resistance is a priority.

How accurate is the movement? Miyota rates the 82S7 at -20 to +40 seconds per day. This is a standard accuracy range for this movement tier.

How do I wind it manually? Rotate the crown clockwise approximately 40 times from a fully depleted state to restore full power reserve.

Is it waterproof for swimming? Yes — rated 50M / 5ATM, suitable for cold bathing and swimming. Not rated for snorkelling or diving.

What size is the case? 50mm in height, 14mm thick, 128g — a large, substantial sport watch with significant wrist presence.