Note: This is a pre-order of the CASE ONLY. Final production may vary slightly from the current specifications. The thinnest Seiko mod case on the market is 9.96 mm. While our design targets a slimmer profile, if the final thickness is slightly higher and does not set a new record, this will not qualify for a refund.

Ultra Thin Yellow Gold Seiko Modding Case

The yellow gold Seikonaut case is designed as part of our pursuit to build the thinnest Seiko modding case in the world. At just 9.95mm with a closed caseback and 10.3mm with an open caseback, it delivers proportions rarely found in the Seiko modding scene, especially for Nautilus-inspired builds.

Compatible With Popular Seiko Movements

This case is fully compatible with Seiko NH35, NH36, NH38, NH70, NH71, and NH72 movements. It also fits a 30.8mm dial, giving modders the flexibility to use classic, skeleton, or open-heart Seiko modding dials.

Correct Nautilus Dimensions

With dimensions of 40mm across (10H–4H) and 38mm from top to bottom (12H–6H), this yellow gold case maintains the balanced proportions required for authentic-looking Seikonaut builds while staying slim and wearable.

Premium Gold Plating

Constructed from 316L stainless steel and finished with a 20 micron thick yellow gold plating, this case exceeds industry standards. Most aftermarket Seiko mod parts use thinner coatings; this plating is more than double the usual thickness, ensuring long-lasting durability and depth of color.

Sapphire Crystal and Water Resistance

The case is fitted with a sapphire crystal, available with either clear anti-reflective coating or blue AR. Water resistance is rated to 50M, giving your Seiko mod both practicality and style.

A Foundation for Luxury Seiko Mods

The yellow gold finish makes this case an ideal choice for those aiming to build a more luxurious Seiko Nautilus mod. With slim engineering, premium materials, and correct proportions, this case is designed to be the foundation for one of your best Seiko modding projects.