SEIKO Original Case Back Gasket - Ref. DC2630N – Special Shape – NOS

Original SEIKO housing gasket (パッキン / Gasket) with part number DC2630N - an original NOS spare part from Japanese stock.
This is a form-fitting seal (not a round O-ring seal) , designed for special SEIKO housings with a square or tonneau-shaped housing .

Technical specifications

• Manufacturer: SEIKO
• Original part number: DC2630N
• Type: Case Back Packing Seal
• Shape: Special shape (rectangular / tonneau / rounded square)
• Condition: New Old Stock (unused, in original packaging)
• Color: Black
• Material: Original SEIKO sealing material (elastomer)

Explanation of the SEIKO part number (coding system)

The part number DC2630N follows the classic SEIKO packing code system , which consists of several logically structured segments:

D

= Seal shape / Cross-sectional shape
→ D = Special shape / not round (for square or tonneau-shaped cases)

C

= Seal width (cross-section)
→ C = 0.90 mm

2630

= Size of the seal
→ 26.30 mm (relevant internal dimension or reference dimension of the housing groove)
For special shapes, the number does not refer to a diameter , but to the relevant housing/slot size that SEIKO uses internally for classification.

N

= Color / Material code
→ N = Black (standard elastomer)

In summary:
DC2630N = black SEIKO housing gasket, special shape , 0.90 mm width , reference size 26.30 mm

Compatibility / Area of ​​application

This seal is used in SEIKO housings with a non-round design , in particular:

• square or tonneau-shaped SEIKO cases
• classic SEIKO models from the 1970s–1980s
• mechanical and quartz models with molded case back

⚠️ Important:
For special shaped seals, exact shape matching is absolutely essential .
The classification is not based solely on millimeter measurements , but also on:

• Case shape
• Seal path
• original SEIKO part number

Installation and maintenance instructions

• Cleaning exclusively with isopropyl alcohol
• Do not use solvents or harsh cleaners
• Lightly coat with sealing grease before installation.
• Always replace old, hardened seals

Scope of delivery

• 1 × SEIKO Original Housing Gasket DC2630N
• in original SEIKO packaging
• unused NOS condition