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Seikonaut Watch Case (CROCODILE LEATHER EDITION) - 40mm


ONLY 4 main components are needed to complete a watch.
Watch Case
Movement Holder (optional)
Tweezer (optional)


  • For a complete watch, select your (1) Dial, (2) Hands and (3) Movement.
  • To have watch assembled, select (4) Assemble Watch. Please note that assembling the entire timepiece requires 2 to 5 business days prior to shipping.

Engineered by us and made exclusively for us with quality assurance by ISO 9001 Certified manufacturers.


From the iconic nautilus and Japanese Seiko comes the hybrid, Seikonaut.

Our own reinterpretation, every part, notches and crevices was redesigned from scratch. Creating a whole new allure and a refinement of the iconic design.

Only 10 pieces were made with these luxurious and genuine Top Grain Crocodile Leather Strap. This bespoke leather strap itself cost much more than the case itself.

This Seikonaut case comes complete with clear AR sapphire, sapphire caseback, screw down crown and crocodile leather strap.

Designed to fit all of our dials (28.5mm) and original NH movements (grey dial holding spacer).

**Please note that assemble watch option will assemble the entire timepiece ready for use and requires 2-5 business days prior to shipping.
    1. Quality Swiss Production Quality, ISO 9001 Certified
    2. Case Material 316L Stainless Steel
    3. Case Diameter 40mm. 43mm with side notches
    4. Case Thickness 12.2mm
    5. Case Length 46mm
    6. Lug Width 10.6mm, 26mm
    7. Strap Type Top Grain Crocodile Leather
    8. Strap Colour Black
    9. Clasp Type Butterfly
    10. Caseback Screw down, Sapphire, Mirror polished
    11. Crown Screw down
    12. Crystal Flat Sapphire with Clear Anti-Reflective Coating
    13. Crystal Size 28mm x 1.7mm
    14. Water Resistant 200m / 20atm
    15. Fit Movements NH35, NH36, NH37, NH38, NH39, NH70, NH71
    1. 1x Watch Case (Inclusive of sapphire, crown, caseback, strap)

    All photos of watches with modification parts are for illustration purposes only and are not included with modification parts purchased.

  • Recommended Mods With:

    1. Swiss Super-LumiNova® BGW9 Hands
    1. A Complete Guide On How To Mod Your SEIKO Watch Dial And Hands (Includes Photos & Video)
    2. Learn about fitting dials with four dial legs

Customer Reviews

Based on 2 reviews
f.p. (Rapolano Terme, IT)
Top case

Best watch

Jack Ott (Sittingbourne, GB)
Using this mod part for: Seiko Samurai
Great Quality!

The quality and finishing of the case is perfect with great attention to detail such as the polished chamfer on the lugs and bezel. The crocodile leather is soft and flexible while perfectly following the contours of the case. I Shall be pairing it with the birch dial and black nautilus hands.