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The Seiko Mod NAUTIKO Green Open Heart is a bold fusion of mechanical strength and refined design. Its 41 mm 316L stainless steel case and integrated bracelet create a durable yet commanding presence, while the sapphire crystal with anti-scratch and anti-reflective treatment ensures long-lasting clarity. The rich green striped dial stands out with luminous indices and hands, while the open-heart window proudly reveals the automatic movement inside.
Powered by the Seiko NH38 automatic movement, this watch embodies mechanical precision and rugged reliability. The screwed crown reinforces toughness, and the exhibition case back showcases the movement at work. Finished with a butterfly clasp for secure comfort and water resistance up to 3 ATM, the Nautilus Green Open Heart is built to endure while standing out with distinctive character.
| Diameter | 41 mm (excluding crown) |
| Thickness | 12 mm |
| Movement | Seiko NH38 automatic movement |
| Glass | Sapphire, anti-scratch with anti-reflective treatment |
| Luminova | Yes |
| Case | 316L stainless steel |
| Crown | Screwed |
| Dial | Green striped dial with open-heart window |
| Bracelet | 316L stainless steel, butterfly style security clasp |
| Lugs | 13 mm |
| Wrist size | 14.5 cm – 22 cm (adjustable) |
| Case back | Crystal (exhibition, visible movement) |
| Water resistance | 3 ATM |
Every watch includes a 2-year warranty against manufacturing defects.
Built for long-term reliability, backed by real support.
30-day money-back guarantee.
Return your watch within 30 days if it’s not right for you.
Personalize your watch with your own logo on the dial.
Every order includes everything you need to enjoy your timepiece from day one:
- Luxury presentation box
- Warranty card
- Mini adjustment toolkit
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The Seiko Mod NAUTIKO Green Open Heart is a bold fusion of mechanical strength and refined design. Its 41 mm 316L stainless steel case and integrated bracelet create a durable yet commanding presence, while the sapphire crystal with anti-scratch and anti-reflective treatment ensures long-lasting clarity. The rich green striped dial stands out with luminous indices and hands, while the open-heart window proudly reveals the automatic movement inside.
Powered by the Seiko NH38 automatic movement, this watch embodies mechanical precision and rugged reliability. The screwed crown reinforces toughness, and the exhibition case back showcases the movement at work. Finished with a butterfly clasp for secure comfort and water resistance up to 3 ATM, the Nautilus Green Open Heart is built to endure while standing out with distinctive character.
| Diameter | 41 mm (excluding crown) |
| Thickness | 12 mm |
| Movement | Seiko NH38 automatic movement |
| Glass | Sapphire, anti-scratch with anti-reflective treatment |
| Luminova | Yes |
| Case | 316L stainless steel |
| Crown | Screwed |
| Dial | Green striped dial with open-heart window |
| Bracelet | 316L stainless steel, butterfly style security clasp |
| Lugs | 13 mm |
| Wrist size | 14.5 cm – 22 cm (adjustable) |
| Case back | Crystal (exhibition, visible movement) |
| Water resistance | 3 ATM |
Every watch includes a 2-year warranty against manufacturing defects.
Built for long-term reliability, backed by real support.
30-day money-back guarantee.
Return your watch within 30 days if it’s not right for you.
Personalize your watch with your own logo on the dial.
Every order includes everything you need to enjoy your timepiece from day one:
- Luxury presentation box
- Warranty card
- Mini adjustment toolkit
The Seiko Mod NAUTIKO Green Open Heart is a bold fusion of mechanical strength and refined design. Its 41 mm 316L stainless steel case and integrated bracelet create a durable yet commanding presence, while the sapphire crystal with anti-scratch and anti-reflective treatment ensures long-lasting clarity. The rich green striped dial stands out with luminous indices and hands, while the open-heart window proudly reveals the automatic movement inside.
Powered by the Seiko NH38 automatic movement, this watch embodies mechanical precision and rugged reliability. The screwed crown reinforces toughness, and the exhibition case back showcases the movement at work. Finished with a butterfly clasp for secure comfort and water resistance up to 3 ATM, the Nautilus Green Open Heart is built to endure while standing out with distinctive character.
| Diameter | 41 mm (excluding crown) |
| Thickness | 12 mm |
| Movement | Seiko NH38 automatic movement |
| Glass | Sapphire, anti-scratch with anti-reflective treatment |
| Luminova | Yes |
| Case | 316L stainless steel |
| Crown | Screwed |
| Dial | Green striped dial with open-heart window |
| Bracelet | 316L stainless steel, butterfly style security clasp |
| Lugs | 13 mm |
| Wrist size | 14.5 cm – 22 cm (adjustable) |
| Case back | Crystal (exhibition, visible movement) |
| Water resistance | 3 ATM |
Every watch includes a 2-year warranty against manufacturing defects.
Built for long-term reliability, backed by real support.
30-day money-back guarantee.
Return your watch within 30 days if it’s not right for you.
Personalize your watch with your own logo on the dial.
Every order includes everything you need to enjoy your timepiece from day one:
- Luxury presentation box
- Warranty card
- Mini adjustment toolkit
Rated 4.8 / 5 based on 811+ reviews across all channels. Showing our top reviews.
4.8
January 15, 2026
Came in a sturdy case with a 2-year warranty card inside. Packaging felt premium, and the sapphire glass looks crystal clear—amazing first impression.
Seikosub Marine Shadow
January 12, 2026
Arrived faster than expected and perfectly packaged. The domed glass gives a beautiful vintage vibe, thanks!
Seikosub Milsub Nato
January 10, 2026
Solid build, vintage diver look, and smooth automatic movement—feels pretty premium on the wrist.
Scubamaster 58
January 8, 2026
The presidential bracelet feels super comfortable and solid. Sapphire glass is spotless, and packaging with the warranty card was a great addition.
Seikodate Champagne
January 5, 2026
Perfect blue tones and great detailing. Shipping was fast, and the watch came well-packed with a warranty card included.
Speedseiko Blue
January 3, 2026
Really like the clean edges and smooth finish on this watch. The brushed steel case looks sharp, and the open-heart dial adds a nice touch. Feels well-built and comfortable on the wrist.
Nautiko Emerald
January 1, 2026
Fantastic quality and great attention to detail. It’s easily my new favorite watch. Shipping was fast, packaging was secure, and I’ll definitely be adding more to my collection.
Seitona Bumble Bee
December 28, 2025
Best purchase I've made in a while. The quality is outstanding and worth every penny.
Nautiko Open Heart
December 25, 2025
The watch arrived spotless—Feels sturdy on the wrist, and the sapphire glass stays perfectly clear.
Seikodate Imperial
December 22, 2025
Superb quality and excellent customer service. This is my favorite MOD store for sure! Love the open back case too.
Nautiko Open Back Case
December 20, 2025
Exceeded my expectations. The details stand out and it feels premium without being over the top. Delivery was smooth and on time. I’ll be ordering again.
Seitona Bumble Bee
December 18, 2025
Came well packed and protected. The watch has a really nice weight to it and the finishing is clean. No complaints at all.
Seikojust Champagne
A Seiko mod is a custom watch built around a reliable Japanese Seiko movement, combined with carefully selected aftermarket components.
At MONOMODS, each watch is hand-assembled using proven automatic or hybrid movements, premium materials, and transparent construction, giving you the freedom to enjoy refined designs without counterfeit products.
The goal is simple:
Luxury-inspired design, built honestly, and made accessible without shortcuts.
Each watch is assembled to order, ensuring proper fit, performance, and quality.
Here’s what to expect:
Once assembly is complete, you’ll receive your track & trace details by email.
Delivery times may vary slightly depending on destination, but you’ll always know where your watch is.
Yes.
There are no surprise charges when your watch arrives.
What you see at checkout is what you pay, simple and transparent.
Yes, personalization is at the heart of what we do.
You can customize:
If you’d like help designing a fully personalized watch, contact us via email or live chat.
We’ll guide you through the process step by step.
Yes.
If you’d like a watch with your own logo, you can contact us by email or live chat and share your logo along with the watch model you prefer.
We’ll create a design mockup for your approval first.
Once you’ve approved the design, we’ll begin assembling your watch.
Email: support@monomods.com
Business Hours: 9:00 AM – 5:00 PM Between Monday to Friday, Timezone: (GMT) Greenwich Mean Time (London)
Address : 71-75 Shelton Street, London,
WC2H 9JQ, United Kingdom
The Seiko Mod NAUTIKO Green Open Heart is a bold fusion of mechanical strength and refined design. Its 41 mm 316L stainless steel case and integrated bracelet create a durable yet commanding presence, while the sapphire crystal with anti-scratch and anti-reflective treatment ensures long-lasting clarity. The rich green striped dial stands out with luminous indices and hands, while the open-heart window proudly reveals the automatic movement inside.
Powered by the Seiko NH38 automatic movement, this watch embodies mechanical precision and rugged reliability. The screwed crown reinforces toughness, and the exhibition case back showcases the movement at work. Finished with a butterfly clasp for secure comfort and water resistance up to 3 ATM, the Nautilus Green Open Heart is built to endure while standing out with distinctive character.
| Diameter | 41 mm (excluding crown) |
| Thickness | 12 mm |
| Movement | Seiko NH38 automatic movement |
| Glass | Sapphire, anti-scratch with anti-reflective treatment |
| Luminova | Yes |
| Case | 316L stainless steel |
| Crown | Screwed |
| Dial | Green striped dial with open-heart window |
| Bracelet | 316L stainless steel, butterfly style security clasp |
| Lugs | 13 mm |
| Wrist size | 14.5 cm – 22 cm (adjustable) |
| Case back | Crystal (exhibition, visible movement) |
| Water resistance | 3 ATM |
Every watch includes a 2-year warranty against manufacturing defects.
Built for long-term reliability, backed by real support.
30-day money-back guarantee.
Return your watch within 30 days if it’s not right for you.
Personalize your watch with your own logo on the dial.
Every order includes everything you need to enjoy your timepiece from day one:
- Luxury presentation box
- Warranty card
- Mini adjustment toolkit
