Seiko Calibre 9S/8L/6S movement family

9S is used in Grand Seiko watches. 8L is used in PROSPEX, PRESAGE, and CREDOR watches. ND58 is used in GSX watches.

8L88/ND58. 43,200 vph. CREDOR and GSX.

ND75.

The 6S mechanical chronograph movement is based on this design.

NC77 = 6S.