The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →The updated SERICA Ref. 5303, introduced in 2023, kept the watch’s established design but changed its movement and internal construction. It replaced the Soprod Newton with a slimmer Soprod M100 automatic caliber, added COSC chronometer certification and incorporated a soft-iron cage for increased magnetic resistance. The result is the Ref. 5303 COSC—not the later, distinct Ref. 5330.
What changed in the 2023 Ref. 5303?
The update was chiefly mechanical. SERICA retained the 5303’s exterior design while fitting a different movement and revising the case construction. The brand’s history identifies the 2023 watch as the Ref. 5303 COSC; the change was covered at the time by Fratello Watches on April 25, 2023.
- New caliber: Soprod M100 replaced the Soprod Newton.
- Official chronometer certification: The M100-equipped version received COSC certification. Fratello reported that the earlier Newton performed within COSC standards but did not have official certification.
- Soft-iron construction: The case incorporates a soft-iron cage intended to protect the movement from magnetic fields.
- Familiar exterior: The update retained the existing aesthetics, materials, finishes and proportions.
Movement and magnetic-resistance specifications
Fratello’s 2023 report gives the Soprod M100 a frequency of 28,800 vibrations per hour, 25 jewels and a 42-hour power reserve. COSC certification distinguishes this version from the previous Newton-equipped model: the earlier movement was described as performing within COSC standards, but it was not officially certified.
Fratello reported magnetic resistance of at least 50,000 A/m for the updated watch, compared with 4,800 A/m for the earlier version. These are figures reported in that 2023 coverage, not independent test results established here. The soft-iron cage is the construction change associated with the higher reported resistance.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →#1 Best Overall
- Movement: COSC-Certified Automatic Mido Caliber 80 Chronometer SI with silicon balance spring. In addition to its non-magnetic properties, it offers greater precision and improved shock resistance. This caliber ensures exceptional autonomy of up to 80 hours.
- This Swiss-made MIDO timepiece, designed to withstand the extreme pressures of the deep sea, is exceptionally water-resistant to 60 bar (600 m/1968 ft). Equipped with a helium valve, it guarantees safe decompression during extended dives.
- Case Type: Stainless steel with ceramic bezel and Sapphire crystal with double sided anti-reflection treatment - Screw-down crown.
- Case Size: 43.5mm - Band Width: 22mm (Tapered) - Case Thickness: 14.55mm
- Strap: Tapered Stainless steel bracelet - Folding clasp with diving extension
Case, bezel and available configurations
The 2023 report lists a 39 mm stainless-steel case, 12.2 mm thick, with a 46.5 mm lug-to-lug length and 20 mm lug spacing. Water resistance is rated to 300 m.
The bi-material, double-scale bezel combines a ceramic minute scale with a steel hour scale. Besides tracking elapsed minutes, its hour scale can be used to follow a second time zone. Fratello listed black, white and crystal-blue dial-and-bezel combinations, paired with a tapered stainless-steel mesh bracelet featuring fitted end links; the updated bracelet clasp is signed.
Rank #2
- Iconic Promaster watches with advanced functions designed to venture to the deepest depths.
- 3 Hand, Date
- Silver-Tone Stainless Steel
- Luminous Hands and Markers and Anti-Reflective Mineral Crystal
- Featuring our Eco-Drive technology – powered by light, any light. 200 Meters Water Resistant and 5 Year Limited Warranty
What did the updated 5303 cost at launch?
Fratello reported a 2023 launch price of €1,490 including tax, compared with €1,290 for earlier versions. That is historical pricing, not a current quote. Current price, stock status and regional availability are not established by the cited coverage.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How the 5303 COSC differs from the later 5330
The Ref. 5330 is a subsequent model, not another name for the 2023 5303 update. SERICA’s history describes it as a later evolution with a redesigned dial, a date window at 3 o’clock, a lighter bezel and a new ceramic shade. In a March 2026 report, Fratello described the 5330’s matte dial and dark-gray ceramic insert, and reported that it retained the M100 movement, 39 mm case and 300 m water-resistance rating. Those later design details belong to the 5330, not the 5303 COSC update.
Rank #3
- Stainless Steel case with Black Resin Band
- Black Dial with date window at 3 O'clock
- Luminous markers and hour hands; sweep second hand
- Anti-reverse bezel
- Water-resistant to 200 M (660 feet)
For watch buyers comparing these references, the practical distinctions are whether the dial has a date, the bezel and ceramic details, and the specific reference being offered. The 5303 update’s defining change is its M100/COSC movement and soft-iron construction within the established 5303 design.
Quick Recap
Best Value
- Single-Button Efficiency: Simplify underwater operation with the Cressi Donatello diving computer's innovative single-button interface, enhancing control for adult divers. Navigate the depths with ease on crisp autumn days, focusing on exploration and adventure
- Air and Nitrox Flexibility: Seamlessly switch between air and nitrox modes with this scuba diving watch, ideal for varied fall diving adventures. Diverse dive types are easily managed, offering versatility in cooler temperatures and shifting underwater conditions
- Freediving Versatility: Enjoy the dual functionality of scuba and freedive sessions with the included freediving gauge mode. Explore fall's underwater beauty with one device that adapts to both breath-hold and traditional diving experiences
- Tailored Ascent Planning: Customize your ascent with user-selectable deep stops on this dive computer watch, ensuring precise planning. Enhance dive safety during fall's cooler waters, aligning with your personal diving preferences and ensuring a smooth ascent
- Cross-Platform Compatibility: Effortlessly review your diving logs with Windows and Mac compatibility, perfect for post-dive relaxation on chilly fall evenings. Dive data is easily accessible, streamlining your digital logging process for future adventures
Rank #4
- Iconic Promaster watches with advanced functions designed to venture to the deepest depths.
- 3 Hand, Date
- Silver-Tone Stainless Steel
- Mineral Crystal
- 200M Water Resistant and 5 Year Limited Warranty
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.
