Guardian of the deep

The power inside a trusted timekeeper.


Developed especially for diver’s watches, the Caliber 8L35 is Seiko’ leading mechanical movement, crafted to the highest standards for performance and functional beauty. Every detail of its construction can be traced back to Seiko’s time-tested expertise in creating cutting-edge mechanical movements from the ground up. What follows are some of the special features that distinguish this high-quality Seiko watch movement.

Unerring precision 
in heat and cold

The balance wheel and hairspring are critical components that ensure a steady beat.Because the balance wheel is made from a sensitive metal,even the slightest temperature change can cause it to expand or contract, potentially leading to distortions in shape.The 8L35 mechanical movement minimizes the effects of temperature on the balance wheel and preserves overall precision by implementing four arms over the usual two or three.To stabilize the rotation,the balance is checked in 0.000001g increments,and then further checked and adjusted by craftsmen and women to as part of a comprehensive quality control process.

A relay race of endurance parts
Power must flow efficiently between the gears with minimal loss of energy for the watch to perform perfectly over time.To ensure efficient transfer of power, gears are elaborately finished using traditional and reliable processing techniques, and are further polished carefully one by one to minimize friction.The escape wheel and pallet fork are created with MEMS (Micro Electro Mechanical Systems), a high-precision component manufacturing method based on semiconductor technology. With MEMS, smooth and precise parts can be made in shapes that are difficult to achieve using conventional methods.Seiko makes the gears using both techniques so that friction is minimized, and every component’s longevity is extended.

Gentle waves flow within
Attention to detail can be observed in the beauty of the movement, even though it is usually hidden behind the case back.The back plate, bridge, and rotor are plated with rhodium, which stands out for its noble, luxurious appearance, and the rotor and bridge are expertly finished with a gentle wave pattern.Our craftspeople ensure that performance and beauty come together in Seiko's leading mechanical movement.

Features of the Movement


SPRON is a Seiko original alloy. Used for the mainspring and hairspring, it was developed to be resistant to tear, corrosion, and wear. The 8L35’s use of this special alloy makes the caliber long-lasting with stable precision.


Diashock is a structure developed to enhance the movement’s resistance to shocks. It is used as a bearing, such as for the balance wheel pivot, a section of the movement that is especially sensitive to shocks and jolts. With Diashock, the structure maintains high stability even when subjected to sudden shocks.

Magic Lever

The Magic Lever serves the important role of efficiently winding the mainspring in an automatic movement. It has two spring pullets of different shapes that are always in contact with the transmission wheel used to rotate the barrel. When the oscillating mass moves in either direction, the two pullets of the Magic Lever always generate unidirectional movement of the transmission wheel. One pulls the transmission wheel and then slips back into place, and the other pushes the same wheel from the opposite side and slips back, enabling efficient winding of the mainspring.

Caliber Number:

Movement Type:
Automatic with manual winding

+15 to -10 seconds per day

Power reserve:
Approx. 50 hours