1
The reference Spring Drive watch.
Grand Seiko Snowflake SBGA211 with Cal. 9R65 Spring Drive: ±1 sec/day, 72-hour reserve, dial textured to mimic snow. The visual reference for Spring Drive.
What Spring Drive actually is
Spring Drive uses a conventional mechanical mainspring to drive a glide wheel, which generates electricity via an embedded coil. The electricity powers a quartz oscillator, which feeds back into an electromagnetic brake on the glide wheel. Result: ±1 second/day accuracy with a continuous, glide-motion seconds hand (no ticking).
Developed by Yoshikazu Akahane at Seiko from 1977, launched commercially in 1999. Production is concentrated at the Shinshu Watch Studio in Nagano, Japan. The technology defines Grand Seiko's identity as the Japanese alternative to Swiss high-end mechanical.
2
Spring Drive caller-GMT.
Grand Seiko Spring Drive Cal. 9R66 with GMT module. Mt. Iwate dial finish. Caller-GMT (less travel-friendly than true GMT) but smoothest GMT-hand sweep in production.
3
Spring Drive moonphase with photographic moon.
Grand Seiko SBGY-series uses a photographic image of the moon (not a stylised face) on a striated dial. Cal. 9R31 Spring Drive moonphase.
4
600m saturation diver with Spring Drive.
Seiko Prospex SBDB025 is the Spring Drive professional diver. 50mm titanium case, 600m water resistance, Cal. 5R65. Marine Master line.
5
Chronograph + GMT + Spring Drive.
Grand Seiko SBGC-series uses Cal. 9R86 Spring Drive Chronograph with GMT. The most complicated Spring Drive at the price.
6
Pink Spring Drive dial, seasonal collection.
Grand Seiko SBGA413 is part of the Heritage Collection seasonal series; the Shunbun reference uses a pink dial with cherry-blossom shading. Cal. 9R65 Spring Drive.
7
Higher-tier Spring Drive with White Birch dial.
Grand Seiko SLGA009 is the Evolution 9 collection White Birch Spring Drive. New 9RA5 movement: 5-day reserve, ±0.5 sec/day. Successor to the standard 9R65.
8
Credor
Eichi II
39mm
Hand-finished Spring Drive at the haute-horlogerie tier.
Credor Eichi II is the hand-finished Spring Drive at the Micro Artist Studio in Shiojiri. Cal. 7R14, ~50 made per year. Japanese haute-horlogerie answer to Lange Saxonia Thin.
9
The 'Tuna' professional diver in Spring Drive.
Seiko Prospex Tuna with Spring Drive: shrouded titanium case, 600m saturation rating, Cal. 5R65. The professional saturation diver Spring Drive.
10
Less-publicised dial-finish variant of the standard Snowflake.
No photo
Grand Seiko Mt. Iwate-finish references use the same Cal. 9R65 with the Mt. Iwate textured dial (slightly different from Snowflake's pure white). Often the value-leading variant in the Spring Drive line.
Honourable mentions
Grand Seiko Sport Spring Drive SBGA-Diver · SBGA231Cal. 9R65 in a sport-diver case at ~€6,200.
Seiko Prospex SBDB031 · DiverSpring Drive saturation diver at ~€4,800.
Credor Lineage · Spring Drive dressMid-tier Credor Spring Drive at ~€18k.
How to choose
Want the canonical Spring Drive: Snowflake SBGA211. Want the latest movement: SLGA009 White Birch with 5-day reserve. Want haute horlogerie: Credor Eichi II. Want professional dive use: Prospex SBDB025 Tuna. The Spring Drive wiki article covers the technology.