Seiko 1M20

Mechanical movements fitted with an oscillating rotor that winds the mainspring through the wearer's natural motion. Invented by Abraham-Louis Perrelet around 1777 for pocket watches and adapted to the wristwatch by John Harwood in 1923, it combines traditional craftsmanship with everyday convenience.

Self-winding via a rotor whose motion winds the mainspring through a transmission gear train. The specific rotor configuration (central, micro, peripheral, bumper) is catalogued separately under Rotor Type. Standard on the vast majority of mechanical wristwatches since the mid-20th century.

The dominant modern system: pulling the crown out to a setting position engages the hand-setting mechanism. Introduced in the late 19th century and refined into multi-position crowns (date, time, GMT). Used in virtually all modern wristwatches and most 20th-century pocket watches.

The undisputed standard of modern mechanical watchmaking. Through an elegant interplay between escape wheel, pallet fork, and balance, it delivers reliable impulses with the safety of 'draw' to keep the lever locked. Refined since the 18th century, it powers almost every quality mechanical wristwatch made today.

The heart of mechanical timepieces, the balance wheel is an oscillating component that, together with the hairspring, forms a harmonic oscillator regulating the gear train's pace. Its steady back-and-forth motion ensures the even release of energy from the mainspring, governing the watch's accuracy.

The most traditional regulator, consisting of a movable index pointer fitted with two curb pins (or a pin and a boot) that embrace the hairspring. Sliding the index along its scale changes the spring's active length, adjusting the rate. Simple, reliable, and easy to service, it remains the workhorse standard across countless mechanical movements.

The most common automatic winding rotor, mounted on the central axis of the movement and rotating a full 360°. Industrialized by Rolex with the Perpetual system in 1931 and refined throughout the 20th century, it offers excellent winding efficiency and remains the de facto standard for automatic wristwatches, whether winding in one or both directions.

It is the most common form that we can find.