Thank you for visiting our store.

This is a vintage SEIKO Grand Quartz 9940-8010 Twin Quartz, one of Seiko's premium high-accuracy quartz watches from the late 1970s.

The Grand Quartz series represented Seiko's top-tier quartz technology, and the Twin Quartz movement was developed to improve temperature compensation and accuracy beyond conventional quartz watches of the era.

This rare vintage model remains highly collectible among Seiko enthusiasts and collectors worldwide.

The watch is currently running and has received a new battery and a new crocodile-pattern leather strap in June 2026.

Features
Genuine SEIKO Grand Quartz
Reference 9940-8010
Twin Quartz Movement
Vintage 1970s Model
High-Accuracy Quartz Technology
Stainless Steel Case
New Crocodile-Pattern Leather Strap (June 2026)
New Battery Installed (June 2026)
Made in Japan
Measurements
Case Diameter: Approx. 35 mm
Lug Width: Approx. 18 mm
Wrist Size: Up to approx. 19.0–19.5 cm
Weight: Approx. 46.6 g

A wonderful addition to any vintage Seiko or Japanese watch collection.

Payment Methods
We accept PayPal and major debit and credit cards. We will ship the item once payment is confirmed.

Payment Process
Please verify your address before placing your order. We will ship only to the address entered at the time of order. We do not accept address changes after an order has been placed.

Shipping
Packaging: Box or envelope, cushioning material (bubble wrap)

After confirming your payment, we will ship your order within the specified timeframe.
Orders placed on weekends will be shipped on Monday or Tuesday. We provide a valid tracking number for all orders.

International Shipping
All international shipments are sent via FedEx, Japan Post, or DHL.
Please note that we may not be able to ship to some areas.

Return Information
We offer a standard 30-day return policy. To receive a full refund, you must return the item in its original, unused condition.The buyer is responsible for the return shipping costs.

To US Buyer
Import duties, taxes, and related customs fees are already included in the item price or shipping cost (DDP: Delivered Duty Paid). You will not be required to pay any additional customs charges upon delivery.

Note: Items over USD 2,500 per transaction (including shipping) or those under the Authenticity Guarantee service may be excluded.