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Jaeger-LeCoultre · Master Ultra Thin

Jaeger-LeCoultre Master Ultra Thin Power Reserve (calibre 938) (pink gold, 9.9 mm high)

Reference Q1372520 · Classic · 39 mm

Ø 39 mmLug-to-lug 46 mm
Illustration drawn from the specifications: case to scale, colours and style approximate. Not a photo. Photos on the official page

Specifications

Reference
Q1372520
Family
Master Ultra Thin
Category
Classic
Status
Current
Case material
18 ct rose gold
Case diameter
39 mm
Case thickness
9.9 mm Official
Lug-to-lug
46 mm Third-party
Lug width
—
Water resistance
50 m
Bezel
—
Calibre
938 Official
Power reserve
70 h
Frequency
28,800 vph (4 Hz)

Official product page · retrieved October 22, 2026

Does it fit your wrist?

Enter your wrist circumference. The watch appears to scale on the flat top of the wrist.

Lug-to-lug 46 mmFlat top of the wrist 54.1 mm
Top view on a wrist, to scale
Flat top of the wrist 54.1 mmLug-to-lug 46 mmCase diameter 39 mm
Side view, across the wrist

Comfortable

Lug-to-lug 46 mm on a flat top of 54.1 mm: 85 % of the width.

Lug-to-lug is 75 to 95% of the flat top, the usual comfortable range.

Measurements and sources

Brands rarely publish thickness, lug width and lug-to-lug together. Each observation below is kept separate, with who gave it.

Case thickness

Value Type Source Date
9.9 mm Official Jaeger-LeCoultre October 22, 2026

Lug-to-lug

Value Type Source Date
46 mm Third-party The 1916 Company Review titled "Jaeger-Lecoultre Ultra Thin Reserve De Marche (Q1372520) Review": "measures 10mm in thickness and 46mm from lug-to-lug". October 24, 2026

Lug width

Lug width is the gap between the lugs, where the strap fits. It is not lug-to-lug.

No source gave this figure yet.

Calibre source

Official Jaeger-LeCoultre · retrieved October 22, 2026

Other Master Ultra Thin references

Watch Ø Thickness Lug-to-lug Calibre
Master Ultra Thin Power Reserve (calibre 938) (pink gold) Q1372510 39 mm 8.95 mm — 938
Master Ultra Thin Date Q1238421 39 mm 7.89 mm 45.8 mm 899
Master Ultra Thin Moon 39 mm Q1368430 39 mm 9.3 mm 45.7 mm 925
Master Ultra Thin Perpetual Calendar Q114842J 39 mm 9.2 mm 45.7 mm 868
Master Ultra Thin Small Seconds Q1218420 39 mm 8.1 mm — 896
Master Ultra Thin Tourbillon (pink gold) Q1682411 40 mm 10.77 mm — 978
Master Ultra Thin Tourbillon Enamel (pink gold) Q13224E2 40 mm 12.13 mm — 978
Master Ultra Thin Tourbillon Moon (pink gold) Q169241J 41.5 mm 12.1 mm — 983
Master Ultra Thin Moon 36 mm Q1248420 36 mm 9.4 mm — 925

Other Jaeger-LeCoultre models

Watch Ø Thickness Lug-to-lug Calibre
Master Control Chronometre Date Power Reserve Q4168120 39 mm 9.2 mm — 738
Master Control Chronometre Perpetual Calendar Q4178180 39 mm 9.2 mm — 868
Master Control Memovox Timer (pink gold) Q410257J 40 mm 12.39 mm — 956
Master Control Calendar Q4148120 40 mm 10.95 mm 47.2 mm 866
Master Control Chronometre Date Q4158120 38 mm 8.4 mm — 899
Master Control Date Q4018421 40 mm 8.78 mm 47 mm 899
Show 38 more
Watch Ø Thickness Lug-to-lug Calibre
Master Control Memovox Q411843J 40 mm 12.39 mm — 956
Duometre Quantième Lunaire (pink gold) Q604242J 42 mm 13.58 mm — 381
Master Grande Tradition Calibre 985 (pink gold) Q5042420 42 mm 13.05 mm — 985
Master Control Classic Q4008520 36 mm 8.15 mm — 899
Master Grande Tradition Calibre 946 (white gold) Q5273480 43 mm 13.42 mm — 946
Master Grande Tradition Calibre 950 (white gold) Q5233420 43 mm 13.7 mm — 950
Rendez-Vous Classic Moon Q3578131 34 mm 9.42 mm — 925
Rendez-Vous Classic Night & Day Q3448111 34 mm 8.63 mm — 898
Reverso Classic Duoface Small Seconds (pink gold) Q3842520 28.3 mm 10.34 mm 47 mm 854
Reverso Tribute Duoface Small Seconds (pink gold) Q3982590 28.3 mm 9.61 mm 47 mm 854
Reverso Tribute Enamel Q39324D2 27.4 mm 8.51 mm 45.6 mm 822
Reverso Tribute Monoface Small Seconds (calibre 822) Q713211J 27.4 mm 7.56 mm 45.6 mm 822
Reverso Classic Duoface Small Seconds 42.9 × 25.5 mm Q2458422 25.5 mm 10.31 mm 42.9 mm 854
Reverso Classic Duoface Small Seconds 47 × 28.3 mm Q3848422 28.3 mm 10.34 mm 47 mm 854
Reverso Classic Monoface 35.78 × 21 mm Q2618540 21 mm 7.4 mm 35.78 mm 657
Reverso Classic Monoface 35.78 × 21 mm (calibre 846) Q2608142 21 mm 7.4 mm 35.78 mm 846
Reverso Classic Monoface 40.1 × 24.4 mm (calibre 657) Q2518140 24.4 mm 7.56 mm 40.1 mm 657
Reverso Classic Monoface Origin Q3878120 16.3 mm 6.95 mm 32.5 mm 657
Reverso Classic Monoface Small Seconds Q2438522 25.5 mm 7.46 mm 42.9 mm 822
Reverso Monoface Q7168420 24.4 mm 7.56 mm 40.1 mm 822
Reverso Small Seconds Q397848J 27.4 mm 8.51 mm 45.6 mm 822
Reverso Tribute Duoface Calendar Q3918420 29.9 mm 10.9 mm 49.4 mm 853
Reverso Tribute Duoface Small Seconds Q3988482 28.3 mm 10.3 mm 47 mm 854
Reverso Tribute Duoface Tourbillon Q392845J 27.4 mm 9.14 mm 45.5 mm 847
Reverso Tribute Enamel (calibre 822) (white gold, 9.73 mm high) Q39334M5 27.4 mm 9.73 mm 45.6 mm 822
Polaris Date (12.9 mm high) Q9128981 40 mm 12.9 mm — 899
Polaris Automatic Q9008170 41 mm 11.2 mm 47.6 mm 898
Polaris Perpetual Calendar (calibre 868) (pink gold) Q908269J 42 mm 11.97 mm — 868
Polaris Perpetual Calendar Q9088180 42 mm 13.07 mm — 868
Master Control Chronograph Calendar Q4138130 40 mm 12.05 mm 47.5 mm 759
Master Control Geographic Q4128421 40 mm 10.96 mm — 939
Polaris Chronograph Q9028170 42 mm 11.92 mm 48.7 mm 751
Polaris Chronograph (calibre 761) Q9028181 42 mm 13.39 mm 48.5 mm 761
Polaris Date Q906863J 42 mm 13.92 mm — 899
Polaris Geographic Q9078640 42 mm 11.54 mm — 939
Polaris Mariner Memovox Q903818J 42 mm 15.63 mm — 956
Reverso Tribute Chronograph Q389848J 29.9 mm 11.14 mm 49.4 mm 860
Reverso Tribute Geographic Q714845J 29.9 mm 11.14 mm 49.4 mm 834

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