Mechanical Open Heart

The bold and luxurious 40mm
mechanical open heart.


Mechanical watches are driven by the force of the mainspring as it gradually unwinds. With an open heart watch you can see the movement of its balance wheel – the beating heart of time – unique to the mechanical system. The three-dimensional layered construction and detailed case design, ideally suited to a 40mm watch face, create a sophisticated look of luxury on the wrist.


On the dial side, a small window at 9 o’clock reveals the movement of the balance wheel – the beating heart of time. The movement has been especially designed for the open heart, where its intricate dance is on full display.

The peaked, tapered hands glisten beautifully in the light, and the layered dial design creates a beautiful contrast with its three-dimensional textures.
These details have all been carefully chosen for a 40mm watch face which creates a striking impression and a sense of luxury.

There are two mechanical open heart models from Knot: the simple, slimmer CAP-38 especially suitable for daintier wrists, and the CAP-40 with its layered dial design, varied textures and larger lug case, making for a more pronounced appearance on the wrist.

Read more about the CAP-38 here

The prominent lug design is an exceptional match for the 40mm case size. Knot uses SUS316L – a high-purity, corrosion-resistant, stainless steel used for medical scalpels – as standard. This material is pleasing to wear even for those with metal allergies, as it produces almost no metal ions.

※This does not exclude the possibility that an allergic reaction could still be experienced by some people.

Sapphire glass crystal is made of the same composition as sapphire gemstone. All Knot watches are created using scratch-resistant sapphire glass which measures 9 on the Mohs Hardness Scale, second only to diamond which is rated 10.




□ Made in Japan
□ Movement: EPSON YN84 (6 beats per second/ Power reserve: 40 hours)
□ Case: SUS316L / polish
□ Glass: sapphire glass (anti-reflective coating)
□ Normal usage accuracy: average -15 seconds to +25 seconds per day (at room temperature: 5°C to 35°C)
□ Water resistance: 5 ATM for everyday life
□ Features: 5hands (hours・minutes・seconds・power reserve・24-hour hand)
□ Number of jewels: 22
□ Size and weight: Diameter 40mm thickness 11mm lug width 18mm weight65g
Silver Case ¥39,600 / IP Color Case ¥41,800

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