The DOXA SUB 300 is the slimmer, 300 m-rated option, while the SUB 300T adds a 1,200 m rating, a helium release valve and a bezel DOXA describes as incorporating a no-decompression dive-time calculator. Both have a listed 42.5 mm case diameter and 38-hour power reserve. The practical choice depends more on which features and case dimensions suit you than on choosing the larger depth rating by default.
How the DOXA SUB 300 and SUB 300T compare
The figures below are specifications published by DOXA for its current Professional models, not independent measurements. Dimensions are listed as diameter × length × height.
| Specification | SUB 300 Professional | SUB 300T Professional |
|---|---|---|
| Case dimensions | 42.50 × 45.00 × 13.40 mm | 42.50 × 44.50 × 13.65 mm |
| Water resistance | 300 m / 30 ATM | 1,200 m / 120 ATM |
| Helium release valve | Not listed on the product page | Listed |
| Bezel | Unidirectional, scale in meters | Unidirectional, scale in feet; DOXA describes an integrated no-decompression dive-time calculator |
| Movement | Swiss automatic; COSC-certified Chronometer; 38-hour power reserve; 28,800 vph | Swiss automatic; 38-hour power reserve; 28,800 vph; COSC certification not stated on the product page |
| Lug width and listed options | 20 mm; beads-of-rice bracelet or FKM rubber strap | 20 mm; bracelet, FKM rubber or NATO |
Sources: DOXA SUB 300 Professional and DOXA SUB 300T Professional product pages, accessed in 2026. Confirm the current specifications for the exact reference and market before buying.
Is the SUB 300T thicker than the SUB 300?
Yes, but only by 0.25 mm according to DOXA’s listed heights: 13.65 mm for the SUB 300T and 13.40 mm for the SUB 300. The listed diameter is the same at 42.5 mm; the T’s listed case length is 44.5 mm, compared with 45.0 mm for the SUB 300. These small differences do not establish how either watch will sit on a particular wrist. If fit is decisive, compare the exact configurations in person.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
What does the SUB 300T add?
Higher stated water resistance and a helium release valve
DOXA rates the SUB 300T to 1,200 m / 120 ATM, versus 300 m / 30 ATM for the SUB 300. The T also lists a helium release valve; the SUB 300 product page does not list one. These are manufacturer specifications, not independent pressure-test results. For most buyers, the greater rating is a specification distinction rather than a reason on its own to choose the watch: match a watch to your intended use and follow professional dive practices.
A different bezel scale and stated function
The SUB 300 bezel is marked in meters. The SUB 300T bezel is marked in feet, and DOXA says it integrates a no-decompression dive-time calculator. Consider which scale and feature set make more sense for your use. A bezel is not a substitute for dive training, planning, or appropriate instruments.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
Movement and certification: what DOXA states
Both product pages list Swiss automatic movements running at 28,800 vibrations per hour (4 Hz), with a 38-hour power reserve. The SUB 300 page explicitly identifies its movement as a COSC-certified Chronometer. The SUB 300T page specifies a Swiss automatic movement but does not state COSC certification. That wording difference is not proof that no SUB 300T version has certification; check the documentation for the exact reference if certification matters to you.
Bracelets, straps and configuration
Both models have a listed 20 mm lug width. DOXA lists the SUB 300 with a beads-of-rice bracelet or FKM rubber strap, and the SUB 300T with bracelet, FKM rubber and NATO options. Lug width alone does not guarantee that a strap or bracelet will fit: check the exact reference, attachment and end-link design, clasp, and strap dimensions before ordering an accessory.
Do these 3 things before closing this tab:
1Scan for outdated or missing drivers - takes under a minute2Clear out junk files and repair common Windows errors3Fix the driver behind crashes, sound loss and screen glitchesRank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
Price and regional availability
DOXA’s US product page displayed $2,190 for the SUB 300T Professional on a stainless-steel bracelet when accessed in 2026. A comparable current US price for the SUB 300 was not established, so that figure should not be treated as a like-for-like price comparison. Prices and available configurations can change; check DOXA or an authorized seller for the current price in your region and the precise bracelet or strap variant.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Historical note on the SUB 300T
DOXA says the modern SUB 300T pays tribute to the SUB 300T Conquistador and dates the modern model’s presentation to September 2019. The manufacturer describes the 1968 Conquistador as the first general-public diver’s watch equipped with a helium release valve. That superlative is DOXA’s historical claim, not an independently verified conclusion here. See DOXA’s SUB 300T Professional description.
Quick Recap
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Which one should you choose?
- Choose the SUB 300 if you prefer its slightly lower listed height, meter-marked bezel, and explicitly stated COSC certification, and its 300 m rating suits your requirements.
- Choose the SUB 300T if you want the listed helium release valve, feet-marked bezel with DOXA’s stated calculator feature, and higher manufacturer-rated water resistance.
- Compare the exact configuration before deciding if case fit, bracelet or strap choice, or price is central to your decision; those details vary by model reference and market.
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.
