CWC RN300 Automatic Diver Mk.1 Tritium With DatevsSeiko Prospex Sea
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Measurements
Catalog photos are all shot at the same flattering size. These aren't: every case below shares one millimeter scale.

RN300 Automatic Diver Mk.1 Tritium With Date

Prospex Sea
Diameter
40mm
41.7mm
Lug-to-Lug
n/a
49.5mm
Thickness
14.5mm
12.3mm
lowest
Water Resistance
300m
highest
200m
Power Reserve
n/a
41h
MSRP
$3,174
$595
lowest
Movement
ETA 2824-2
Seiko 4R35
Case
4 specsCrystal & Dial
3 specsMovement
3 specsPricing
1 specsReviews
Synthesized for each watch independently from owner discussions, enthusiast forums, written reviews, and video reviewers.
Owners widely praise the CWC (Cabot Watch Company) RN300 Automatic Diver Mk.1 Tritium Watch With Date for its robust build, military heritage, and iconic design elements like the big triangle and sword hands, with many finding its case finishing excellent and its bezel action satisfyingly chunky and precise. The watch is noted for its good lume and legibility, and some owners appreciate its polished steel finish and vintage vibe. Accuracy figures vary, with one owner reporting +1 second per day and another seeing 3 seconds fast over 24 hours. A point of contention for some is the fixed lug bars, which limit strap options, and a few reviewers feel the price has increased significantly, making it harder to justify compared to other brands. Overall, owners and reviewers rate the CWC (Cabot Watch Company) RN300 Automatic Diver Mk.1 Tritium Watch With Date highly for its sturdy, utilitarian design and military significance.
Owners widely report the Seiko Prospex Sea is a well-built watch at a fair price, with some finding its 41.7mm case size perfect while others with smaller wrists consider it big, thick, and heavy. Reviewers consistently praise the excellent lume and robust design. One owner notes the bezel action is smoother and more precise than some other Seiko divers. Overall, owners and reviewers rate the Seiko Prospex Sea highly for its value and proven design.
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