SEIKO Original Housing Seal OB2070 (1 piece) – O-ring (Ø approx. 20.7 mm / 0.75 mm)

SEIKO 純正部品 パッキン – Made in Japan

Genuine SEIKO housing gasket with part number OB2070 , manufactured according to the classic SEIKO sealing system (OLD scheme). It is a precisely defined O-ring with an inner diameter of approximately 20.7 mm and a cross-section of 0.75 mm , as used in numerous SEIKO housings.

Technical data

• Manufacturer: SEIKO
• Part number: OB2070
• Type: Housing seal / O-ring
• Inner diameter: approx. 20.7 mm
• Cross-section / thickness: approx. 0.75 mm
• Cross-sectional shape: round (O-shaped)
• Color: black
• Material: synthetic sealing rubber (SEIKO standard)
• Condition: NOS (New Old Stock)
• Scope of delivery: 1 piece
• Origin: Japan

Explanation of the SEIKO coding system (OLD)

SEIKO marked seals according to a functional dimension and shape code :

• 1st position (letter): Cross-sectional shape (O = O-ring)
• 2nd position (letter): Thickness/width (B ≈ 0.75 mm)
• Numeric keypad: Inner diameter size class
• Last digits: serial or tolerance index

➡️ This allows exact original dimensions to be derived – unlike generic O-rings.

Usage / Compatibility

• SEIKO Quartz & Mechanical Models
• Small to medium-sized cases
• Press-fit or screw-in bottoms
• Always select by part number, not by "approximate diameter".