Seiko Mods Glossary – Seiko watch terms explained
A
Aftermarket parts
Watch components not supplied by the original manufacturer. Common in watch modding for cases, dials, hands, bezels, or crystals.
Applied Indices
Applied hour markers on the dial create depth and a sense of value.
Automatic
A mechanical watch that winds itself through the movement of the wrist.
Automatic movement
Clockwork mechanism with rotor that operates without a battery.
B
Lug Width
Distance between the band lugs, important for choosing the right bracelet.
Bezel (lunette)
Ring around the glass, fixed or rotatable, often with a scale (diver, GMT).
Bezel insert
Inlay in the bezel made of ceramic, aluminum or steel.
Base (Caseback)
Back of the housing, screwed or pressed, open or closed.
C
Case (housing)
The outer casing of the watch determines its size, shape, and water resistance.
Chapter Ring
Ring between dial and glass, usually with minute markers.
Chronograph
Watch with stopwatch function; in Seiko Mods often only as a design element.
D
Date
Calendar display of the day, usually positioned at 3 o'clock.
Diver-style
Diver's watch design with a distinctive bezel and good readability.
Dress Watch
Elegant watch with a simple design, often with a flat construction.
G
Power reserve
The length of time a mechanical watch runs after being fully wound.
Housing diameter
Diameter of the watch without crown, often between 39–42 mm.
Housing (316L stainless steel)
The outer casing protects the movement and dial; material and workmanship influence durability and wearing comfort.
Suitable watches:
Glass (sapphire glass)
Scratch-resistant watch glass, frequently used in high-quality mod watches.
Suitable watches:
GMT
Additional hand for displaying a second time zone (useful when traveling).
Suitable watches:
GMT movement
Automatic movement with GMT function (second time zone).
Suitable watches:
H
manual winding
Mechanical movement that is wound manually.
Hardlex
Hardened mineral glass, originally developed by Seiko.
I
Indices
Hour markers on the dial, printed or applied.
Insert
Short form for bezel insert.
K
Ceramic bezel/ceramic insert
Highly scratch-resistant bezel or bezel insert; popular in diver and GMT designs.
Suitable watches:
compatibility
Perfect fit of parts to movement, case or dial.
complication
Additional function of a watch, e.g. date or GMT.
L
Lug-to-Lug
Distance from one strap end to the other – crucial for wearing comfort.
Lume (luminous material)
Luminous material on hands and indices for readability in the dark.
M
Mod/Modding
Modification or assembly of a clock from various components.
Movement (clockwork)
Mechanical inner workings of the watch.
N
Nautiko/Nautilus-Style
A sporty-elegant "integrated" look, often with a flat silhouette.
Suitable watches:
NH34
Seiko automatic movement with GMT function.
NH35
Very common Seiko automatic movement (often with date), known for its robustness and good serviceability.
Suitable watches:
NH36
NH35 variant with day and date display.
O
Open Heart
Cutout in the dial that reveals parts of the clockwork.
OEM
Original parts from a manufacturer, rarely used in modding.
Oyster style
Sporty bracelet style with a three-row metal band.
P
Power Reserve
English term for power reserve.
Push-pull crown
Crown without screw mechanism.
R
Rehaut
Inner ring between glass and dial.
rotor
Movable component in the automatic movement that takes over the lifting mechanism.
S
sapphire crystal
Highly scratch-resistant watch glass, standard on high-quality Seiko Mods.
Seamaster-style/Diver-style
Diver's watch look with sporty bezel, high readability and robust construction (style term).
Suitable watches:
Seikoak/Royal Oak style
Sporty-elegant look with integrated band aesthetics (style term).
Suitable watches:
Seikojust (Datejust-Style)
Classic, elegant style, often with a date-themed design.
Suitable watches:
Seiko Mod
Custom-built watch based on Seiko-compatible movements.
visible floor
Case back with glass for viewing the movement.
steel bracelet
Stainless steel bracelet, robust and durable.
Sub-style
Colloquial term for diver design.
T
Tolerances
Manufacturing tolerances of components are important for fit accuracy.
U
clockwork
The mechanics of the watch determine its accuracy, functions, and running behavior.
V
Screw-down crown
Crown with screw mechanism to increase water resistance.
W
Waterproofing
Water resistance is specified in ATM or meters.
Z
pointer
Components for displaying hours, minutes, seconds and additional functions.
dial
Designed surface of the clock with markings, textures and colors.
Dial feet
Small pins for attaching the clock face to the clock mechanism.