Side by side

Sinn 103 StvsFormex Reef 39.5 mm

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

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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.

Sinn 103 St

The Sinn 103 St is widely praised for its classic chronograph appeal and purposeful 41mm size, with owners finding the Ty Hd variant stunning in person. Reviewers highlight its domed acrylic crystal and consider the model an outstanding value for the money. Some owners note the 103 St Sa E's 17mm thickness may be an issue, despite its wearable case dimensions. The Sinn 103 St is also recognized as a space-capable watch, having been worn on a MIR mission. Overall, owners and reviewers rate the Sinn 103 St highly for its classic chronograph design and strong value proposition.

Formex Reef 39.5 mm

The Formex Reef 39.5 mm is widely praised for its refined finishing, comfortable and well-proportioned case design, and impressive specifications for its price point, including COSC-certified Sellita SW300-1 movement and 300m water resistance. Owners and reviewers highlight the tool-less micro-adjust clasp and quick-release spring bars as practical features. Some reviewers note that the 22mm lug width feels slightly disproportionate to the smaller case, and the bracelet could benefit from more taper, though this is a point of contention for some owners who value the overall package. A prototype crown protrusion issue is noted as being addressed for production. On balance, owners and reviewers rate the Formex Reef 39.5 mm highly for its excellent value and well-executed design.

At a glance

20 of 29 specs differ
Diameter
103 St41mm
Reef 39.5 mm39.5mm
Power Reserve
103 St48h
Reef 39.5 mm56h
Water Resistance
103 St200m
Reef 39.5 mm300m
MSRP
103 St$2,538
Reef 39.5 mm$2,230

Full specifications

Case

8 specs
Category
Tool
Diver
Diameter
41mm
39.5mm
Thickness
15.5mm
11mm
Lug-to-Lug
45.5mm
Lug Width
20mm
22mm
Finish
polished
Water Resistance
200m
300m
Caseback

Crystal & Dial

6 specs
Crystal
Acrylic
Sapphire
Crystal Shape
AR Coating
Dial Color
Black
Bahama Blue
Indices
Lume
Luminescent
Super-LumiNova

Movement

5 specs
Caliber
Concepto C99001
Sellita SW300-1
Beat Rate
28,800 vph
0 vph
Power Reserve
48h
56h
Jewels
25
0
Complications
Date, Day-Date, Chronograph, Pilot's Bezel
None

Pricing

1 specs
MSRP
$2,538
$2,230
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