Seiko 8L35 is an automatic movement and a close cousin of 9S55. Seiko 8L35 caliber is one of the first movements assembled in Morioka Seiko’s Instruments Inc. workshop nested in Shizukuishi, under the Mount Iwate mountain and established in 1970. Caliber 8L35 was specially designed for diver’s use.
However, 8L35 was not the ideal movement for the Prospex divers at the early stage; performance dive watches often need a solid sturdy case back for intense water resistance, 8L35 was not the suitable one. The 8L series were mainly used for the Seiko Brightz. Since 2015, Seiko began using the micro-electromechanical parts, which made it easier for 8L35 to fit for performance diver watches; 8L35 are selected and used for the premium high-end Prospex.
Caliber 8L35 Automatic Jewels 26 Frequency 28,800 A/h Power Reserve ~50 hours Rotor Direction: Bi-directional Automatic Winding, Seiko Magic Lever Winding Hand-Windable: Yes Functions Hours, minutes, central second hand, date window at 3:00, quick date correction
Accuracy messes no more than -10/+15 seconds per day in normal temperature conditions (5-35 °C).