SpecStudio
Click to inspect
Seiko Prospex Alpinist Mechanical
Ref. SPB123J1
Stock unknown
Case
- Diameter
- 39.5mm
- Thickness
- 13.2mm
- Lug-to-lug
- 46.4mm
- Lug width
- 20mm
- Material
- Stainless Steel
- Water resistance
- 200m
- Caseback
- See-through screw case back
Crystal & dial
- Crystal
- Sapphire
- Dial colour
- Cream
- Indices
- Applied gold Arabic numerals at 12/2/4/6/8/10 with applied gold triangular batons at the remaining hours
- Lume
- Lumibrite on hands and indexes
Movement
- Caliber
- Seiko 6R35
- Type
- Automatic
- Jewels
- 24
- Complications
- Date, Hacking seconds, Internal rotating compass bezel
Seiko
Seiko's upgraded automatic caliber offering a substantial 70-hour power reserve, nearly double the 4R35 it replaces in higher-end Presage and Prospex models. The extended reserve is achieved through a longer mainspring while maintaining the same 21,600 vph beat rate. Accuracy is tightened to -15/+25 seconds per day compared to the 4R35's wider tolerance. Represents Seiko's push to compete with Swiss movements offering 80-hour reserves.
Market
RetailNot listed
The forum market
See what sellers are asking.
Active listings0Across watch forums
Closed · 90d1Asking-price history
See the asking prices behind closed forum listings. Market+ adds medians with their sample sizes and the weekly trend.
Retail stock & market context
Seiko on the secondhand market
+10.4%
2026 so far · +6.1% to +17.3% · 91 matched watches
In line with the index
Year-by-year readings →Similar watches
Community
Owners widely praise the Seiko Prospex Alpinist Mechanical for its distinctive design, with many highlighting the sunburst dial, gold indices, and compass bezel as key aesthetic draws. The watch is considered by some to be the best iteration of the Alpinist line, featuring a thinner case and improved scratch resistance. However, the stock strap is often seen as adequate but prompts personalization. One owner notes the difficulty in sourcing a spare strap. While some owners express satisfaction with the watch's beauty, one owner finds the specs average for the price point and is hesitant about the cost. The mechanical nature of the watch raises concerns for active outdoor use due to potential damage from hard hits. Overall, owners rate the Seiko Prospex Alpinist Mechanical highly for its striking design and character.
Open the discussion
On real wrists
No shots yet. Show how it wears.
Related
In collections
