Mechanics

Complications

Tap parts of each dial to learn how the mechanism works.

Tap ⊕ to add up to 3 for comparison

1821, Nicolas Rieussec

Chronograph

Measures elapsed time with start, stop and reset pushers.

Difficulty

●●●○○

Added parts

~125

Rarity

common

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How it works

A column wheel or cam coordinates clutches that engage the chronograph gear train with the seconds wheel.

Why collectors love it

Mechanical timing, a direct link to motorsport and aviation heritage.

Mini gallery

Column Wheel

The crown jewel, coordinates clutch and brake.

Heart Cam

Geometry that guarantees instant reset to zero.

Tachymeter

Bezel scale converts elapsed seconds to speed.

Famous examples

Omega SpeedmasterRolex DaytonaZenith El Primero

1954, Rolex × Pan Am

GMT

Shows a second time zone via a 24-hour hand and bezel.

Difficulty

●●○○○

Added parts

~35

Rarity

common

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How it works

An additional wheel geared 2:1 against the hour wheel drives the 24-hour hand.

Why collectors love it

Essential for travelers; pioneered for transatlantic pilots.

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Pepsi Bezel

Red & blue, the original travel uniform.

Office GMT

Caller-style: GMT hand jumps, local hour fixed.

True GMT

Flyer-style: local hour jumps independently.

Famous examples

Rolex GMT-Master IIGrand Seiko SBGETudor Black Bay GMT

16th century

Moonphase

Displays the current phase of the lunar cycle.

Difficulty

●●○○○

Added parts

~12

Rarity

uncommon

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How it works

A 59-tooth wheel advances once a day, showing two moons through a half-disc aperture.

Why collectors love it

Poetic, astronomically accurate, deeply traditional.

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Bombé Moon

Hand-painted, gold-leaf stars on lacquered night.

Astronomical

Accurate to one day in 122 years on top calibers.

Double Aperture

Two moons share a 59-tooth eternal dance.

Famous examples

Patek Philippe 5396A. Lange Saxonia MoonphaseBlancpain Villeret

1762, Thomas Mudge

Perpetual Calendar

Tracks day, date, month and leap year, correctly until 2100.

Difficulty

●●●●●

Added parts

~275

Rarity

grand

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How it works

A mechanical memory of cams and levers knows month lengths and leap cycles.

Why collectors love it

Among the most prestigious complications in watchmaking.

Mini gallery

48-Month Cam

Four years of memory on a single brass star.

Grand Lever

Reads the cam, jumps date 1–3 days at month-end.

Until 2100

Only needs correction at non-leap centuries.

Famous examples

Patek Philippe 5320GAP RO PerpetualLange Langematik Perpetual

1996, Patek Philippe

Annual Calendar

Auto-corrects all months except February.

Difficulty

●●●○○

Added parts

~95

Rarity

uncommon

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How it works

A simpler cam system distinguishes 30 and 31 day months.

Why collectors love it

Most of the convenience, a fraction of the cost.

Mini gallery

One Setting / Year

Adjusts every March 1, that's the only maintenance.

Triple Aperture

Day, date, month, Patek's 5396 signature layout.

Smart Cam

Knows 30 vs 31, doesn't know leap years.

Famous examples

Patek Philippe 5396Lange Saxonia Annual

1933, Breguet

Power Reserve

Shows remaining stored energy in the mainspring.

Difficulty

●●○○○

Added parts

~28

Rarity

uncommon

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How it works

A differential gear translates winding state into hand position.

Why collectors love it

Practical, know when to wind.

Mini gallery

Up / Down

Pocket-watch heritage display, F to E arc.

8-Day Movement

Twin barrels stretch reserve past a week.

Caseback View

Often shown on movement side for collectors.

Famous examples

A. Lange Lange 1Panerai Luminor PRIWC Big Pilot 7-day

1687, Daniel Quare

Minute Repeater

Chimes the time on demand via tiny hammers and gongs.

Difficulty

●●●●●

Added parts

~340

Rarity

grand

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How it works

A slide arms snail cams that release hammers striking gongs for hours, quarters, minutes.

Why collectors love it

Acoustic artistry, the soul of haute horlogerie.

Mini gallery

Cathedral Gongs

Long, wrapped twice, deepest tone in horology.

Snail Cams

Three nested cams encode hours, quarters, minutes.

All-or-Nothing

Safety piece prevents partial chimes mid-strike.

Famous examples

Patek 5178GAP RO Concept RepeaterVacheron Patrimony Repeater

1801, Abraham-Louis Breguet

Tourbillon

Rotates the escapement to average out gravity.

Difficulty

●●●●●

Added parts

~70

Rarity

grand

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How it works

Balance wheel and escapement sit in a cage rotating once per minute.

Why collectors love it

Pinnacle of mechanical artistry.

Mini gallery

Flying Tourbillon

Cantilevered cage, no upper bridge, unobstructed view.

Double-Axis

Cage within a cage, defeats gravity on two planes.

60-second Cycle

One full rotation per minute since 1801.

Famous examples

Breguet Classique TourbillonGreubel Forsey 24 SecondesAP RO Tourbillon