Terminologies Explained

About Movement

Seiko NH35 (date only) and NH36 (day and date) automatic movements are the common ones to mod with. Currently, the market price for a new NH35 movement is $45–80, whereas the price of NH36 is slightly higher because of its additional day wheel.

NH35 and NH36 are automatic movements, which means they each have a rotor /metal weight at the bottom that rotates and winds up the movement when it’s in motion. In this way, if you wear the watch frequently enough, the automatic movement will have a perpetual motion on your wrist.

About Case Models

The model number and nickname of watches can be confusing. Here’s a guide to some common Seiko models on their names, dimensions, and stories behind them.

SKX007

- 42.5mm wide, 13mm thick
- Seiko's legendary diver water model, discontinued in 2019
- “SKX007 conversion case” means a case model that’s compatible with SKX007 parts; “SKX007 Sub” means a SKX007 conversion case that’s similar to Rolex Submariner.

SKX007

SRPD

- 42.5mm wide, 13mm thick
- The successor of SKX007 with minor alterations
- A major critique is its comparatively lack of water resistance due to the absence of screw-down crown.

SKX007 (left) and SRPD (right)

Seiko 6105 / “Captain Willard”

- 44mm wide, 13mm thick
- Gained its nickname because Captain Willard famously wore it in the cult-classic Apocalypse Now
- The legendary Japanese explorer Naomi Uemura–the first man to reach North pole solo and first man to raft the Amazon solo –famously wore this model on several expeditions.