SEIKO Original Case Back Gasket - Ref. EC3160B – 31.6 mm – NOS

The original SEIKO case gasket ( part number EC3160B ) is from old stock (NOS) and is designed for numerous classic SEIKO watches. It seals the case back and is a typical replacement part for servicing and professionally repairing vintage SEIKO models.

Technical specifications

• Manufacturer: SEIKO
• Original part number: EC3160B
• Type: Case Back Packing Seal
• Condition: New Old Stock (unused, in original packaging)
• Color: Black
• Material: Original SEIKO sealing material (rubber / elastomer)

Mass:

• Inner dimension (diameter): 31.6 mm
• Seal width (cross-section): 0.90 mm

Explanation of the SEIKO part number (coding system)

The part number EC3160B follows the classic SEIKO packing code system. Each part of the number has a specific technical meaning:

E
= Case Back Packing Seal

C
= Width / Thickness of the seal
→ Code C corresponds to 0.90 mm

3160
= Size of the seal in millimeters , without decimal point
→ 3160 = 31.60 mm internal dimension
Measurements are taken between the 3 o'clock and 9 o'clock positions (inner dimension of the sealing groove).

B
= Color or material variant
→ B = Black

In summary:
EC3160B = black SEIKO housing gasket with 31.6 mm inner dimension and 0.90 mm width

Compatibility / Area of ​​application

This gasket is used in numerous SEIKO vintage cases with a corresponding case back diameter, especially in models from the 1960s–1980s (mechanical and quartz).

⚠️ Note:
The size is determined by measurements , not solely by model name. Please check before purchasing:

• Check the inner dimension of the case base groove (31.6 mm)
• Compare seal width (0.90 mm)

Installation note

• Clean with isopropyl alcohol only
• Do not use solvents or harsh cleaners
• For optimal sealing, lightly grease (watch seal grease)

Scope of delivery

• 1 × SEIKO Original Housing Gasket EC3160B
• in original SEIKO packaging