



Seiko Prospex Automatic Sumo 45mm SPB101J
4 interest free payments of $350.00
The Seiko Prospex Sumo SPB101J— Made in Japan—is a bold and iconic diver’s watch beloved by Seiko fans around the world. Nicknamed the “Sumo” for its powerful case shape, broad stance, and distinctive 12 o’clock marker, this model embodies strength, durability, and unmistakable Seiko character.
The classic black dial of the Seiko SPB101J is paired with large LumiBrite hands and markers for exceptional underwater visibility, while the robust stainless‑steel case and bracelet deliver reliability in demanding conditions.
Powered by Seiko’s high‑performance 6R35 automatic movement, the SPB101J offers an impressive 70‑hour power reserve and the precision engineering Seiko is renowned for. With a sapphire crystal, screw‑down crown, unidirectional rotating bezel, and 200m water resistance, this Prospex diver carries forward Seiko’s heritage of pioneering dive‑watch craftsmanship since the debut of Japan’s first diver’s watch in 1965.
What we love about the Seiko Sumo SPB101J. The SPB101J captures everything that makes the Sumo a fan favourite—rugged presence, exceptional build quality, and brilliant legibility. The black dial adds a modern twist to a true Seiko classic, while the 6R35 movement provides dependable, long‑lasting performance. It’s a standout diver that blends heritage, precision, and everyday wearability in one unmistakable design.
Orders are dispatched within 1–3 business days from Sydney via Australia Post Express for fast and reliable delivery. Customers located in Sydney may also enjoy the convenience of same‑day Click & Collect, with orders ready for pickup from our Alexandria showroom just one hour after purchase when this option is selected at checkout.
Every watch is covered by a 3‑year Seiko Australia warranty, providing complete peace of mind. StarBuy is an Authorised Seiko Distributor, and all watches are supplied in genuine Seiko original packaging. Warranties are registered online directly with Seiko, and following dispatch, Seiko will email you confirmation of your warranty registration along with a link to the online instruction manual. In line with Seiko’s current sustainability practices, printed warranty booklets and manuals are no longer supplied.
Specification
Case
- Case Diameter (mm) 45mm
- Case Thickness (mm) 12.9mm
- Lug-to-Lug (mm) 52.6mm
- Lug Width (mm) 20mm
- Case Material Stainless Steel
- Case Shape Round
- Case Back Type Solid Case Back
- Glass Type Sapphire Crystal
- ISO Dive Certified Yes
- Water Resistance (m) 200
- Bezel Material Aluminium Bezel
- Bezel Type 120-Click Unidirectional Rotating Bezel
Bracelet / Strap
- Material Stainless Steel
- Type Bracelet
- Interchangeable? Yes
- Clasp Deployment Clasp
- Clasp Type Push Button
Dial
- Colour Black
- Calendar Date
- Finish Matte Dial
- Indices Type Batons, Dots
Delivery
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How and when will my StarBuy order be shipped?
We ship all orders via Australia Post Express for fast and reliable delivery. We aim to dispatch every order as quickly as possible—typically within 1–3 business days. You'll receive a confirmation email with tracking details as soon as your order ships. -
Can StarBuy guarantee delivery dates?
While Australia Post Express is generally reliable, their delivery dates are estimates only and may vary, especially during busy periods. We appreciate your understanding if your parcel takes a little longer to arrive. -
Will I need to sign for my order?
Yes, a signature is required upon delivery. If no one is home, we recommend using a work address. Australia Post may offer contactless delivery—in those cases, we follow their current safety protocols. Risk and ownership transfer to the recipient upon delivery. -
What if I am not home when my order arrives?
If no one is available to sign, Australia Post will leave a card with details on how to collect your parcel from the closest authorised Australia Post Office. You’ll need to present a photo ID at the post office to pick it up. If you’ve authorised a Safe Drop with Australia Post previously, they’ll follow your existing instructions. -
Will I get a Shipping Notification?
Absolutely! As soon as your order is on its way, you’ll receive an email with tracking details. We kindly ask for your patience—tracking updates may take up to 3 business days after ordering. -
What are your shipping charges?
We offer free shipping Australia-wide with Australia Post Express. For approved brands shipped to New Zealand, a $10 flat fee will be added to your total at checkout. Approved parcels to NZ are shipped within the Australia Post / NZ Post network. -
Click & Collect?
Prefer a quicker pick-up? Our Click & Collect service makes it easy.
Pickup Location:
StarBuy
Suite 23, 112 McEvoy Street
Alexandria NSW 2015Hours:
Monday–Friday: 10am–5pm
Saturday: 9am–12pmHow it works - Your order will be ready for pickup within an hour during business hours (unless otherwise notified). If someone else is collecting on your behalf, just email us their name—they’ll need to show ID at pickup.
FAQ
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Are all items in stock?
StarBuy products for sale on the website are always live and accurate. All items marked ‘In Stock’ are physically in stock with us. Items marked ‘Out of Stock’ are completely sold out. In rare instances where additional items are ordered and the items are being shipped to StarBuy, a specific note will be made on the product page.
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How can I be sure your products are authentic?
We guarantee that all of the products we sell on StarBuy- Are brand new
- Are 100% genuine - manufactured by the named brands, in keeping with their high quality standards.
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Is a tax invoice included with my order?
All orders have an automated invoice emailed to the email address on the order. All items listed on our website are GST inclusive. The invoice clearly shows the GST charged on the purchase as well as our name and ABN number.
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Can an item be reserved or put on hold?
Unfortunately due to the model adopted by StarBuy, we are unable to reserve or put an item on hold. Items on sale are limited in quantity and often sell out quickly.
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Why are StarBuy prices low?
StarBuy is a low cost discount website that buys items in bulk and offers them at the lowest possible prices. We keep our costs low by automating most back office processes to keep our prices world competitive. We ensure that you benefit by buying quality brands at low prices from StarBuy and come back to save money again and again.
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Specifications
- Case Diameter (mm) 45mm
- Case Thickness (mm) 12.9mm
- Lug-to-Lug (mm) 52.6mm
- Lug Width (mm) 20mm
- Case Material Stainless Steel
- Case Shape Round
- Case Back Type Solid Case Back
- Glass Type Sapphire Crystal
- ISO Dive Certified Yes
- Water Resistance (m) 200
- Bezel Material Aluminium Bezel
- Bezel Type 120-Click Unidirectional Rotating Bezel
- Material Stainless Steel
- Type Bracelet
- Interchangeable? Yes
- Clasp Deployment Clasp
- Clasp Type Push Button
- Colour Black
- Calendar Date
- Finish Matte Dial
- Indices Type Batons, Dots
- Type Automatic
- In House? Seiko In House Movement
- Calibre 6R35
- Beat Rate (vph) 21600 vph
- Jewels 24
- Movement Hacking? Yes
- Hand Winding? Yes
- Self Winding? Yes
- Power Reserve (days) 2.91 days
- Accuracy +25 to -15 Seconds per Day
- Reference SPB101J
- GTIN 4954628230201
- Display Analog
- Gender Male
- Age Group Adults
- Weight (g) 190g (Approximate)
- Shipping Period 1-3 Business Days - Sydney
- Brand Seiko
- Authorised Dealer Yes
- Warranty Period Seiko 3 Year
- Warranty Registration Online by Starbuy
- Warranty Provider Seiko Australia
- Packaging Seiko Official Packaging
- Manual Seiko Online
- Service Centre Seiko - Sydney
Reviews
Need help?
Frequently Asked Questions
What strap size fits the Seiko Sumo SPB101J, and can I change the bracelet?
The SPB101J has a 20mm lug width, so any standard 20mm strap fits. Because of the Sumo's curved case profile, curved-end rubber or fitted aftermarket straps sit flush against the case, while straight-end NATO and leather straps will show a small gap at the lugs. The supplied stainless steel bracelet has a three-fold clasp with push-button release and a diver's extender for wear over a wetsuit, and links can be removed for sizing by any watchmaker.
What movement does the Seiko Sumo SPB101J use, and how accurate is it?
The SPB101J runs Seiko's in-house 6R35 automatic movement with hand-winding and hacking seconds, an approximately 70-hour power reserve, and a rated accuracy of +25 to −15 seconds per day. The 6R35 replaced the earlier 6R15 used in previous Sumo generations, nearly doubling the power reserve — the watch will comfortably keep running over a full weekend off the wrist.
Does the Seiko Sumo SPB101J have a sapphire crystal?
Yes. Unlike earlier Sumo generations that used Seiko's Hardlex mineral glass, the third-generation SPB101J is fitted with a scratch-resistant sapphire crystal, alongside a 45mm stainless steel case, 200m ISO diver's water resistance, screw-down crown, and LumiBrite on the hands, indexes and bezel. Despite the 45mm diameter, the 52.6mm lug-to-lug and 12.9mm thickness mean it wears more compact than the number suggests.