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1Fix the driver behind crashes, sound loss and screen glitches2Repair Windows errors before they cause bigger problems3Scan for outdated or missing drivers - takes under a minuteThe Bremont Terra Nova Jumping Hour in stainless steel is offered in 38mm and 40.5mm versions, with different lug widths and configurations. The exact reference matters: the 40.5mm steel-bracelet model has 22mm lugs, while the cited 38mm steel-bracelet model has 20mm lugs. Bremont lists the 40.5mm watch at $4,300 on a bracelet or $4,000 on leather on its US collection page; these are listed prices, not a promise of current availability or transaction price.
Which Terra Nova Jumping Hour stainless-steel version is this?
“Terra Nova Jumping Hour” covers more than one configuration. Bremont lists 38mm and 40.5mm cases, with variations in straps and dial treatments. The specifications below distinguish the cited steel-bracelet references; check the exact reference and dial before buying, comparing fit, or ordering an accessory.
38mm and 40.5mm specifications
| Specification | 38mm steel bracelet | 40.5mm steel bracelet |
|---|---|---|
| Reference | TN38-JH-SS-CC-B | TN40-JH-SS-BK-B |
| Case diameter | 38mm | 40.5mm |
| Case length | 44mm | 47mm |
| Case depth | 9.1mm | 10.15mm |
| Lug width | 20mm | 22mm |
| Calibre | BC634AH | BC634AH |
| Jewels | 29 | 29 |
| Frequency | 28,800 beats per hour (4Hz) | 28,800 beats per hour (4Hz) |
| Power reserve | 56 hours | 56 hours |
| Water resistance | 3 ATM / 30 metres | Not stated on the cited product page |
Figures are from Bremont’s official US product specifications, accessed in 2026. The 40.5mm collection page describes the case as 904L stainless steel and identifies the movement as BC634; verify the selected reference’s own product listing for its complete specification.
How does the jumping-hour display work?
Rather than showing the hour with a continuously moving hand, the watch displays it in an aperture. Bremont describes a mechanically actuated hour disc that advances sharply at the change of hour. Its 38mm listing says the jump takes under one tenth of a second; that is Bremont’s stated specification, not an independent measurement.
#1 Best Overall
- 1.316L Stainless Steel Case/Screw Crown/Steel Closed Caseback
- 2. Seagull ST1721 Jump Hour Mechanical Movement
- 3. Sapphire Crystal / Diameter: 34.5MM / Case Thickness : 10.4MM / Lug to Lug =45MM
- 4.Comfortable Rubber Strap /5.Butterfly Clasp
- 5.Band Width: 20MM*18
The hour and minute each have a separate aperture, while a central display or hand indicates running seconds. Aperture placement and dial treatment vary, so inspect the specific version rather than assuming every Terra Nova Jumping Hour has the same layout. The format suits readers who like a clear, window-based hour indication; anyone who prefers reading the hour from a conventional hand may find it less intuitive.
Choosing a size and strap
Choose by case footprint, not diameter alone
The 38mm version is also shorter and thinner in the cited specifications: 44mm long and 9.1mm deep, compared with 47mm and 10.15mm for the 40.5mm model. Those differences can affect how much wrist space the watch occupies, but dimensions alone cannot determine comfort on every wrist.
Rank #2
- 1.316L Stainless Steel Case/Screw Crown/Steel Closed Caseback
- 2. Seagull ST1721 Jump Hour Mechanical Movement
- 3. Sapphire Crystal / Diameter: 34.5MM / Case Thickness : 10.4MM / Lug to Lug =45MM
- 4.Comfortable Rubber Strap /5.Butterfly Clasp
- 5.Band Width: 20MM*18
Match any replacement strap to the exact reference
The cited 38mm bracelet reference has 20mm lugs and the 40.5mm bracelet reference has 22mm lugs. A strap sized for one therefore should not be assumed to fit the other. Confirm the reference and lug width before purchasing a replacement, and check the selected model’s dial and attachment details as well.
Bracelet or leather on the 40.5mm collection
Bremont’s US collection page lists the 40.5mm model with either a 904L steel bracelet or leather strap. On that page, the listed prices are $4,300 for steel and $4,000 for leather, accessed in 2026. These are manufacturer-listed US prices; they do not establish current stock, prices in other regions, or the final price offered by a retailer.
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Quick Recap
Best Value
- Premium Stainless Steel Construction: 316L stainless steel case with screw crown and steel closed caseback for durability and longevity
- Seagull ST1721 Jump Hour Mechanical Movement: Features reliable automatic mechanical movement with unique jumping hour complication
- Comfortable Genuine Leather Strap: Equipped with genuine leather strap and pin buckle for secure and comfortable wear
- Sapphire Crystal Protection: AR coated sapphire crystal provides scratch resistance and clarity with diameter of 39mm, case thickness of 10.4mm, and lug to lug measurement of 46.8mm
- Standard Band Width: 20mm to 18mm band width allows for easy strap replacement and customization options
Rank #4
- 1.316L Stainless Steel Case/Screw Crown/Steel Closed Caseback
- 2. Seagull ST1721 Jump Hour Mechanical Movement
- 4.Comfortable Genuine Leather Strap with pin buckle
- 6. AR Coated Sapphire Crystal / Diameter: 39MM / Case Thickness : 10.4MM / Lug to Lug =46.8MM
- 7.Band Width: 20MM*18
Rank #3
- 1.316L Stainless Steel Case/Screw Crown/Steel Closed Caseback
- 2. Seagull ST1721 Jump Hour Mechanical Movement
- 3. Sapphire Crystal / Diameter: 34.5MM / Case Thickness : 10.4MM / Lug to Lug =45MM
- 4.Comfortable Rubber Strap /5.Butterfly Clasp
- 5.Band Width: 20MM*18
What to verify before buying
- Confirm whether the listing is for the 38mm or 40.5mm case and match the reference number.
- Check whether the watch comes on a steel bracelet or leather strap; the cited prices apply to the 40.5mm US collection listings.
- Review the exact dial and aperture arrangement in the product listing.
- Use the reference-specific lug width when selecting an aftermarket strap.
- For water use, rely on the water-resistance rating published for the precise reference. The cited 3 ATM / 30 metres figure belongs to the 38mm listing and should not be applied to the 40.5mm model without its own confirmation.
Official Bremont listings
- Terra Nova 40.5 Jumping Hour collection and listed US configurations
- Terra Nova 40.5 Jumping Hour, Steel Bracelet
- Terra Nova Jumping Hour Steel, Bracelet, 38mm
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
