What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Bremont’s Terra Nova Jumping Hour is offered in 904L stainless steel in two distinct case sizes: 38mm and 40.5mm. They are not simply the same watch in different dimensions—their display layouts differ, and the published 38mm specifications should not be assumed to apply to the 40.5mm model.
What is a jumping-hour watch?
A jumping-hour watch shows the hour as a numeral in an aperture rather than on a conventional central hour hand. The hour changes discretely at the appropriate point in the cycle; minutes are read separately. On the Terra Nova, the arrangement depends on the size: the 38mm model places the hour window at 12 and the minute window at 6, while the 40.5mm collection listing describes offset hour and minute apertures with a left-to-right flow.
Bremont says the 38mm model’s hour disc jumps in under a tenth of a second. That is the manufacturer’s description, not an independently measured result. The company identifies the movement as BC634 and says it was developed in partnership with Sellita.
What changes between the 38mm and 40.5mm steel versions?
| Detail | 38mm steel model | 40.5mm steel model |
|---|---|---|
| Case material | 904L stainless steel, according to Bremont’s product page (Bremont 38mm product page) | Polished and brushed, cushion-shaped 904L stainless steel, according to Bremont’s US listing (Bremont 40.5mm product page) |
| Display | Hour aperture at 12, minute aperture at 6, and central running seconds (Bremont 38mm product page) | Offset hour and minute apertures, described as flowing left to right, with central seconds (Bremont 40.5mm product page) |
| Published dimensions | 38mm diameter; 44mm case length; 9.1mm depth; 20mm lug width (Bremont 38mm product page) | Not stated in the cited Bremont listing |
| Movement and reserve | BC634AH; 29 jewels; 28,800 bph (4Hz); 56-hour power reserve (Bremont 38mm product page) | BC634 Jumping Hour calibre; reserve and detailed movement specifications not stated in the cited listing (Bremont 40.5mm product page) |
| Water resistance | 3 ATM/30m, as listed by Bremont (Bremont 38mm product page) | Not stated in the cited Bremont listing |
The 38mm page also specifies a Glucydur balance wheel, Anachron balance spring, and Nivaflex mainspring. Those details, like its dimensions and water-resistance rating, belong to the 38mm listing; they should not be transferred to the larger version without confirmation.
#1 Best Overall
- HEART RATE TRACKING - Monitor heart rate to optimize workouts, 24/7 tracking with notifications if heart rate is too high or too low, and overnight heart rate variability to track health over time.
- MENSTRUAL CYCLE GUIDE - This smartwatch is great for women to log cycle phases, period duration, period symptoms, flow and moods over time to create a personalized routine to align with your needs.*
- ADVANCED 24/7 ACTIVITY TRACKING - 40+ activities recognized with heart rate zones during workout, Fitness Level via VO2 max and connected GPS tracker. Track your trends to improve your performance.
- SLEEP TRACKER - Wake up to your Sleep Quality Score, improve your energy levels with insight into your sleep metrics: light sleep, deep sleep, duration, disturbances, interruptions and regularity.
- 30-DAY BATTERY & EXTRA DURABILITY - Enjoy 24/7 tracking for up to 30 days on a single charge, comes with docking station, USB-C compatible. Made with premium materials for extra durability.
What does “now in steel” mean?
For these listings, steel means 904L stainless steel, not a newly introduced movement or a single universal Terra Nova configuration. Bremont’s 40.5mm page describes a gloss black dial and a polished-and-brushed cushion-shaped case. The 38mm steel model has its own vertically arranged hour and minute apertures. Check the exact reference and product page when comparing photographs or specifications.
Bracelet or leather strap: which configuration?
Bremont’s US 40.5mm listing showed the bracelet configuration at $4,300 and the leather-strap configuration at $4,000 when checked in 2026. These are live-listing prices observed for the US market, not a historical price announcement; current prices and stock may differ. The configurations are listed on Bremont’s 40.5mm product page.
Rank #2
- From the Bulova Men's Classic Collection, inspired by vintage design, our classic watches achieve a tailored, discover a bold collection of diamond watches.
- 6 Hand, Chronograph, High Performance Quartz
- Silver-Tone Stainless Steel
- Mineral Crystal
- 100M Water Resistant and 3 Year Limited Warranty
For the 38mm bracelet model, Bremont describes a 904L bracelet with articulated links, quick release, and a butterfly clasp (38mm bracelet product page). Do not assume those bracelet details—or the 38mm model’s 20mm lug width—apply to the 40.5mm version. Verify strap or bracelet compatibility against the precise reference before ordering.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What does 3 ATM/30m water resistance mean here?
The 3 ATM/30m rating is published for the 38mm steel model only. It is a stated pressure rating, not a guarantee that the watch is suitable for swimming, diving, or every real-world water exposure. Bremont’s cited 38mm page does not establish a specific water-use recommendation, and the cited 40.5mm listing does not state a comparable rating. Follow the current manufacturer guidance for the exact reference and have seals checked as appropriate.
The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Quick Recap
Best Value
- Paying tribute to the legendary performer, the Frank Sinatra collection incorporates vintage Bulova designs with unmistakable elements of the iconic singer.
- 3 Hand, Small Second Hand
- Silver-Tone Stainless Steel
- Curved Sapphire Crystal
- 30M Water Resistant and 3 Year Limited Warranty
Rank #4
- Bulova's Men's Classic Sport collection exploring functionality and sport design that's always in style.
- Chronograph, Calendar
- Silver-Tone Stainless Steel
- Mineral Crystal
- 100M Water Resistant and 3 Year Limited Warranty
Rank #3
- Bulova's Men's Classic Sport collection exploring functionality and sport design that's always in style.
- 6 Hand, Chronograph, 24 Hour Time
- Silver-Tone Stainless Steel with Blue Silicone Strap
- Mineral Crystal
- 100M Water Resistant and 3 Year Limited Warranty
Who should consider the steel Terra Nova Jumping Hour?
- Choose between 38mm and 40.5mm by looking at both case scale and display placement: the smaller listing has vertically arranged apertures, while the larger collection listing uses offset windows.
- Compare bracelet and leather options only within the exact reference shown on Bremont’s live listing.
- Treat Bremont’s movement specifications and jumping-time description as manufacturer claims; the cited product pages do not establish independent performance testing or long-term reliability.
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.
