Side by side

Bremont ionBirdvsSeiko Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch

The numbers, the dial colors, the calibers — laid out so you can stop flipping between tabs.

ionBird
BremontionBird
MSRP $5,800

At a glance

15 of 29 specs differ
Diameter
ionBird43mm
Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch39.5mm
Power Reserve
ionBird40h
Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch45h
Water Resistance
ionBird
Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch200m
MSRP
ionBird$5,800
Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch$2,800

Full specifications

Case

7 specs
Category
Pilot
Diver
Diameter
43mm
39.5mm
Thickness
12.3mm
Lug-to-Lug
47.2mm
Lug Width
20mm
Material
Titanium
Stainless Steel
Water Resistance
200m

Crystal & Dial

4 specs
Crystal Shape
Flat
Box
AR Coating
Inner
Anti-reflective coating on inner surface
Dial Color
Regular length (15cm - 19cm wrist size)
Black
Lume
None
LumiBrite on hands, index(es) and bezel

Movement

3 specs
Caliber
6L37
Power Reserve
40h
45h
Jewels
25
26

Pricing

1 specs
MSRP
$5,800
$2,800

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What people say

Owners + reviewers, side by side

Synthesized for each watch independently from owner discussions, enthusiast forums, written reviews, and video reviewers.

Bremont ionBird

Owners report the Bremont ionBird is overpriced and features a printed dial with a poorly placed date window at 4:30, which some find visually disruptive. However, some owners suggest its case finishing is superior to competitors. The 43mm titanium Bremont ionBird GMT is powered by a COSC-certified BE-93-2AV automatic movement and retails for $5,795. On balance, owners and reviewers find the Bremont ionBird's date window placement and price point to be significant drawbacks.

Seiko Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch

The Seiko Prospex Marinemaster 1965 Heritage Diver's Watch is praised for its faithful re-creation of the 62MAS design, with reviewers noting improved wearability due to smaller case sizes (38mm to 40mm) and updated bracelets. Specific models feature a stainless steel case with super-hard coating, ceramic bezel, and a tool-free extension system on the bracelet. Accuracy figures vary, with one model rated at -5/+10 seconds per day and another at -10/+15 seconds per day, powered by movements like the Caliber 8L45 or 6L37 offering 72-hour or 46-hour power reserves respectively. Some reviewers point out drawbacks such as an unsigned winding crown, a lack of tool-free micro-adjust on the clasp for certain models, and a secondary GMT function on one variant. The price point, ranging from $2,800 to $3,600, is considered high by some, especially when compared to other Seiko or Grand Seiko offerings.

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