Seiko uses the Superior and VFA brands to indicate specially tuned movements.
Seiko VFA Movements
Seiko uses the initials VFA to indicate a movement tuned to high accuracy. This is typically included on the dial of the watch, often as V.F.A..
Seiko Superior Movements
Superior is a brand name used by Seiko to indicate specially-tuned watches with high accuracy. It is similar to Seiko Special and was also sometimes called GFA to position it above Seiko VFA.