



Seiko Prospex Tuna Automatic Black Dial Silicone Strap Men's Watch SLA042J1
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Seiko Prospex Tuna Automatic Black Dial Silicone Strap Mens Watch SLA042J1
The Case:
The Dial:
This model features simplified indices making it easy to read underwater. Both these indices and hands feature Seiko's own luminous coating, which is called LumiBrite, to allow for easy visibility at night or the unknown of the ocean. Replacing the 3 o'clock index is a date window which uses the same colour scheme as the dial, a black dial and white markers. The chapter ring displays the seconds in standard line markers, again a simple yet effective style.
The Strap:
The accordion-style silicone strap combines high durability and comfort - a strap design invented by Seiko in 1975 as a practical solution to the expansion and contraction of a diver's wrist at different depths. A standard buckle can then be easily fastened to sit comfortably around your wrist.
The Functions:
Power to the watch is provided by an automatic movement. The calibre used in particular is a Seiko exclusive, called the 8L35. An automatic movement is powered by kinetic movement and once kick started should keep time due to the natural notion of the wrist throughout the day. Moreover, the calibre has a manual wind capacity whereby power can be supplied by spinning the crown. A power reserve of 50 hours allows you to put the watch and your wet-suit away for the weekend to come back to on Monday morning. 26 jewels all work independently to provide an accuracy of +15 to -10 seconds per day which is seen as a standard in diver's watches. Yet another feature of the movement is a stop second hand function which stops the second hand once screwed out. This allows for precision timing in crucial moments. Finally, the watch has a water resistance of 1000 metres, suitable for saturation diving.
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UK Delivery
| Selling Price | Royal Mail 48 (Tracked) |
Royal Mail 24 (Tracked & Signed) |
Special Delivery Next Day (Mon – Fri) |
Special Sunday Delivery (Before Sat 12pm) |
Royal Mail Special Delivery by 1pm |
|---|---|---|---|---|---|
| £0 to £99.99 | FREE | £4.99 | £7.99 | £7.99 | £9.99 |
| £100 to £499.99 | N/A | FREE | £7.99 | £7.99 | £9.99 |
| £500 or more | N/A | N/A | FREE | £7.99 | £9.99 |
We know your order is important to you, so we use Royal Mail’s tracked delivery service on all UK orders.
We also offer Royal Mail Special Delivery service, which for an additional fee offers guaranteed delivery the next day before 1pm.
*Royal Mail Tracked 24 and Royal Mail Tracked 48 services are 98% accurate but not guaranteed.
Orders placed before 5pm (Monday–Friday) are dispatched the same day. Orders placed on Saturday or Sunday are dispatched the following Monday.
International Shipping & Duties (Delivered At Place – DAP)
We’re pleased to offer worldwide delivery with fully tracked and insured shipping.
How international orders work
All international orders are shipped on DAP (Delivered At Place) terms. This means:
- The price you pay at checkout covers your goods and international shipping only.
- WatchNation does not collect or charge any overseas sales tax, import VAT, or customs tariffs (duties).
- When your order reaches your country, local customs authorities may apply:
- Import VAT (value-added tax),
- Tariffs or customs duties (import taxes based on product category and value), and
- Handling or clearance fees from the courier.
These charges are set by your country’s customs authority and are payable by you before delivery.
You’ll be contacted directly by DHL with a secure link to pay any applicable charges. Once cleared, your parcel will be released and delivered promptly.
Estimated delivery times (after dispatch)
- European Union: approximately 2–5 working days
- Rest of World: approximately 5–7 working days
Customs processing times vary by country and may extend delivery slightly.
If import charges, tariffs, or duties are not paid
If local charges are unpaid or delivery is refused, the shipment will be returned to us. In this case, we will refund your order minus the outbound shipping cost and any return or customs fees billed to us by the carrier.
Estimating import costs
Import VAT and duty rates vary by country. You can check estimated import taxes and tariffs by contacting your local customs authority or using your government’s online import calculator.
More about delivery...

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Frequently Asked Questions
Yes — we are an Authorised Dealer for every brand we sell. All watches come with an official box, papers, and a full manufacturer’s warranty.
Every watch includes a manufacturer warranty. You’ll find more warranty info listed in the product description.
Orders placed before 5pm (Mon–Fri) are dispatched the same day. Order before 12pm on Sat for same-day dispatch. Free UK delivery is available on all orders, and tracking details are provided once shipped.
Yes — you have 14 days from delivery to return or exchange your item, provided it’s unused and in its original packaging.

