Side by side

Longines ULTRA-CHRON CLASSICvsYema Skin Diver CMM.20

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

ULTRA-CHRON CLASSIC
LonginesULTRA-CHRON CLASSIC
MSRP $3,900
Skin Diver CMM.20
YemaSkin Diver CMM.20
MSRP $2,372

At a glance

23 of 29 specs differ
Diameter
ULTRA-CHRON CLASSIC37mm
Skin Diver CMM.2039.5mm
Power Reserve
ULTRA-CHRON CLASSIC52h
Skin Diver CMM.2040h
Water Resistance
ULTRA-CHRON CLASSIC50m
Skin Diver CMM.20200m
MSRP
ULTRA-CHRON CLASSIC$3,900
Skin Diver CMM.20$2,372

Full specifications

Case

9 specs
Category
Diver
Diameter
37mm
39.5mm
Thickness
10.95mm
11.5mm
Lug-to-Lug
44.6mm
47mm
Lug Width
19mm
20mm
Material
Stainless Steel
316L Stainless Steel
Finish
Brushed and polished
Water Resistance
50m
200m
Caseback
Screw-down case back
Solid

Crystal & Dial

6 specs
Crystal
Sapphire
Domed Sapphire
Crystal Shape
Flat
AR Coating
Both sides
Inner
Dial Color
Silver
Black
Indices
Applied indexes
Applied
Lume
Super-LumiNova
None

Movement

7 specs
Caliber
L836.6
Yema CMM.20
Beat Rate
36,000 vph
28,800 vph
Power Reserve
52h
40h
Jewels
0
25
Hacking
No
Yes
Hand-winding
No
Yes
Complications
Hours, minutes, seconds and date
None

Pricing

1 specs
MSRP
$3,900
$2,372

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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.

Longines ULTRA-CHRON CLASSIC

The Longines ULTRA-CHRON CLASSIC is widely praised for its faithful retro design, high-beat 5Hz movement offering greater precision and a smooth seconds hand, and its value proposition as a new 5Hz watch. Reviewers highlight the L836.6 caliber's TimeLab "ultra chronometer" certification for superior accuracy and shock recovery, and owners find the bracelet very comfortable with easy micro-adjust. Some owners note the design appears dated, and one reviewer points out the dial lacks luminescence and water resistance is only 50m. Owners are split on sizing, with some finding the 40mm case wears larger than expected and recommending the 37mm version. Overall, owners and reviewers rate the Longines ULTRA-CHRON CLASSIC highly for its blend of vintage aesthetics, modern high-beat movement performance, and comfortable wearability.

Yema Skin Diver CMM.20

Owners and reviewers widely praise the Yema Skin Diver CMM.20 for its vintage aesthetic, 39mm-39.5mm case size, and the in-house CMM.20 micro-rotor movement. The watch features a textured cream dial, sharp applied indices, and a satisfyingly over-engineered push-to-turn bi-directional bezel. The fully brushed bracelet with toolless micro-adjust clasp is highlighted as a significant improvement, though some note its extended lug-to-lug may challenge smaller wrists. Accuracy figures range from -3/+7 seconds per day to erratic results between 0 and -10 seconds per day, with a 70-hour power reserve. Some owners express concerns about the brand's QC reputation and the micro-rotor movement's performance, while one reviewer noted questionable finishing on a prototype's hour hand and a rattly clasp. Overall, owners and reviewers rate the Yema Skin Diver CMM.20 highly for its vintage styling and improved bracelet at the price.

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