SPB121 vs SPB155
Two Prospex field watches on the same 6R35 movement.
The differences that matter
- Size: the SPB121 is 1.5 mm wider (39.5 vs 38 mm).
- Movement: both use the 6R35.
- Availability: the SPB121 is no longer sold new by Seiko US, so it is mostly bought pre-owned; the SPB155 is still sold new.
Side by side
| SPB121 | SPB155 | |
|---|---|---|
| Price | $725 | $725 |
| Size | 39.5 mm × 13.2 mm | 38 mm × 12.9 mm |
| Strap width | — | 20 mm |
| Comes on | — | — |
| Water resistance | 200 m | 200 m |
| Sapphire crystal | Yes | Yes |
| Lume | — | Hands and markers |
| Screw-down crown | — | Yes |
| Movement | Automatic, hand-winding | Automatic, hand-winding |
| Bezel | — | No rotating bezel listed |
| Hacking seconds | Yes | Yes |
| Hand-winding | Yes | Yes |
| Power reserve | About 70 hours | About 70 hours |
Figures come from each watch’s sources, listed on its own page.