Movement
Spring Drive
A mechanical mainspring regulated with quartz precision.
- Typical accuracy
- About ±1 second per day (±15 seconds per month).
How it works
Seiko's Spring Drive powers the watch with a traditional mainspring, but replaces the mechanical escapement with a 'Tri-Synchro Regulator': a glide wheel braked electromagnetically and governed by a quartz reference. The result is a mechanical watch with quartz-level accuracy and a perfectly continuous — not ticking — seconds hand.
Strengths
- Quartz accuracy with a mechanical soul
- A truly gliding seconds hand
- No battery — self-winding versions exist
- A genuine feat of engineering
Trade-offs
- Expensive and largely exclusive to Grand Seiko/Seiko
- Specialist servicing only
- Polarizing among mechanical purists
Care tips
How to keep one running well between services.
- Service only through Seiko's specialist network
- Keep it wound (wear or winder) for best accuracy
- Same magnetism and shock precautions as any fine mechanical watch
Keep reading
- Movement
Solar (Light-Powered)
Light charges a cell that can run for months in the dark.
- Movement
Meca-Quartz
Quartz timekeeping with a mechanical chronograph.
- Movement
Kinetic
Wrist motion generates electricity for a quartz movement.
- Movement
Tuning Fork (Accutron)
A humming fork instead of a ticking balance wheel.
- Movement
Digital (LCD/LED)
A quartz movement with a screen instead of hands.
- Complication
Date
The most common complication — the day of the month.