Updated
Seiko 5 Sports GMT SSK001 vs Tudor Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet)
Seiko's GMT watch meets Tudor's diver
Quick Verdict
The Seiko 5 Sports GMT SSK001 ($250–$500) offers Seiko In-House Automatic GMT precision in the tier below the Tudor Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet) ($2,500–$5,000). The 5 Sports GMT SSK001 measures 42.5mm and is rated 100m (10 ATM). The Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet) counters with Swiss Made craftsmanship and 200m (20 ATM) water resistance. Both are exceptional watches for their respective tiers.
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Tudor
Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet)
$2,500–$5,000
Specifications Compared
| Feature | Seiko 5 Sports GMT SSK001 | Tudor Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet) |
|---|---|---|
| Price | $250–$500 | $2,500–$5,000 |
| Case Size | 42.5mm | 39mm, 14.6mm thick, 20mm lugs |
| Movement | Automatic Caliber 4R34 (True GMT) | Tudor manufacture calibre MT5652, automatic GMT with independently adjustable hour hand, COSC chronometer, bidirectional rotor |
| Caliber Type | Seiko In-House Automatic GMT | Tudor manufacture MT5652, COSC |
| Power Reserve | 41 Hours | About 70 hours |
| Water Resistance | 100m (10 ATM) | 200m (20 ATM) |
| Crystal | Hardlex Crystal | Domed sapphire |
| Case Material | Stainless Steel | Stainless steel, polished and satin; fixed 24-hour graduated bezel in satin-brushed steel; screw-down crown |
| Origin | Made in Japan | Swiss Made |
Category-by-Category Analysis
Design & Aesthetics
Seiko's design language vs Tudor's approach
The Seiko 5 Sports GMT SSK001 features a Stainless Steel case at 42.5mm with Hardlex Crystal protection. The Tudor Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet) offers Stainless steel, polished and satin; fixed 24-hour graduated bezel in satin-brushed steel; screw-down crown construction at 39mm, 14.6mm thick, 20mm lugs with Domed sapphire. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Automatic Caliber 4R34 (True GMT) vs Tudor manufacture calibre MT5652, automatic GMT with independently adjustable hour hand, COSC chronometer, bidirectional rotor
The 5 Sports GMT SSK001 runs the Automatic Caliber 4R34 (True GMT) (Seiko In-House Automatic GMT, 41 Hours power reserve) at 21,600 vph (3 Hz) frequency. The Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet) uses the Tudor manufacture calibre MT5652, automatic GMT with independently adjustable hour hand, COSC chronometer, bidirectional rotor (Tudor manufacture MT5652, COSC, About 70 hours reserve) at standard. The Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet) offers a longer power reserve.
Wearability & Fit
42.5mm vs 39mm, 14.6mm thick, 20mm lugs — different wrist presence
At 42.5mm, the 5 Sports GMT SSK001 has a bolder wrist presence compared to the Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet) at 39mm, 14.6mm thick, 20mm lugs. Water resistance differs: 100m (10 ATM) vs 200m (20 ATM).
Value & Cost of Ownership
Seiko sits in the lower tier
The Seiko 5 Sports GMT SSK001 sits at $250–$500 and the Tudor Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet) at $2,500–$5,000. On the specs that outlast any price: the 5 Sports GMT SSK001 uses Hardlex Crystal with 41 Hours, against Domed sapphire and About 70 hours on the Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet). Service intervals are typically 5-7 years for both.
Water Resistance
100m (10 ATM) vs 200m (20 ATM)
The 5 Sports GMT SSK001 is rated to 100m (10 ATM) while the Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet) handles 200m (20 ATM). The Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet) offers superior water resistance.
Our Verdict
Seiko
5 Sports GMT SSK001
Choose the Seiko 5 Sports GMT SSK001 if you prioritize Seiko In-House Automatic GMT engineering, Made in Japan craftsmanship, and 100m (10 ATM) water resistance. At $250–$500, it delivers Automatic Caliber 4R34 (True GMT) with 41 Hours power reserve.
Check Price on AmazonTudor
Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet)
Choose the Tudor Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet) if you value Tudor manufacture MT5652, COSC technology, Swiss Made heritage, and 39mm, 14.6mm thick, 20mm lugs proportions. At $2,500–$5,000, the Tudor manufacture calibre MT5652, automatic GMT with independently adjustable hour hand, COSC chronometer, bidirectional rotor with About 70 hours power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Seiko 5 Sports GMT SSK001 and Tudor Black Bay Pro 39mm M79470-0001 (steel, fixed 24-hour bezel, black dial, riveted steel bracelet) represent two distinct approaches to fine watchmaking — the Seiko bringing Made in Japan tradition while Tudor delivers Swiss Made engineering.
Frequently Asked Questions
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How This Page Was Made
Our comparisons are generated from a hand-maintained specification database and reviewed under our editorial standards. We use AI tools to assemble pages from that data. We don’t invent specs: every number traces back to the database, and when we correct an entry, the fix is applied site-wide. As an Amazon Associate, The Horologist earns from qualifying purchases.