What's the difference between the Miyota 8215, 8315 and 9015?
The Miyota 8215, 8315 and 9015 movements are mechanical automatic movements, but they differ in features and intended use.
The Miyota 8215 is a robust and proven entry-level automatic movement. It offers automatic winding, hand winding and a date display.
The Miyota 8315 is based on the 8215, but offers a higher power reserve. This means the watch keeps running longer when it's not being worn.
The Miyota 9015 is built flatter, designed for greater precision and features hacking seconds. It's often used in higher-quality or particularly slim automatic watches.
In short: the 8215 is robust and reliable, the 8315 offers more power reserve, and the 9015 is technically more refined, flatter and more precise.