SBDX001 vs SLA023
Geth put them head to head in "SBDX001 VS SLA023. Similar yet different". Scores, specs and verdicts side by side.
Seiko · Prospex Marinemaster
Seiko SBDX001 Marinemaster 300
10/10
Unreal scenario
Gethin's grail: the original Marinemaster 300, which he would take over the SLA023 'all day long'.
Seiko · Prospex Marinemaster
Seiko SLA023 Marinemaster 300
9/10
Beyond thunderdome
His grail and favourite Marinemaster: an unmatched Zaratsu case, the best bezel action and handset he's ever known and Christmas-tree lume. The Prospex X, the painted triangle and the unregulated movement are the only things stopping it being perfect.
The winner: Seiko SBDX001 Marinemaster 300
The 023 has the better bezel action and brighter loom, no argument. But if you ask me which one I'd like to own, it's the original, all day long, every single day. The lacquered bezel, the clean dial and that protected pip get it there.
Spec sheets
| SBDX001 | SLA023 | |
|---|---|---|
| case diameter (mm) | 44 | 44.3 |
| thickness (mm) | 15.4 | 15.4 |
| lug to lug (mm) | 50 | 50 |
| lug width (mm) | 20 | 20 |
| weight (g) | – | 222 g with all links (about 205 g with a link out each side), said of both MM300s stated by gethin |
| case material | Steel, no Diashield coating (brighter steel than the SLA023); monocoque case with Zaratsu polishing | 316L stainless steel ('I believe') with Diashield coating (about 500 Vickers vs 250), duller and greyer than the SBDX001; monocoque case, brushed midcase, Zaratsu polish on the top of the flanks, drilled lugs |
| crystal | Double-domed Hardlex (not sapphire) | Flat sapphire with an internal dome (AR coating inside) |
| water resistance (m) | 300 | 300 |
| crown | Unsigned | Screw-down, signed (laser-etched 'Prospex X'), at 4 o'clock |
| caseback | – | Monocoque, no removable caseback; tsunami wave on the back. Not limited. His is a March 2021 J1 |
| bezel | Lacquered (not ceramic or DLC), scratches easily; shrouded lume pearl at 12, no lume on the bezel otherwise | 120-click unidirectional, ceramic insert, coin-edged; unprotected painted lume triangle instead of a shrouded pip, lumed to the 20-minute marker. His has a dent from a car seatbelt buckle; Seiko quoted GBP 500 for a replacement bezel. In the Jan 2023 strap video he also says it is 'slightly misaligned' |
| dial | Black; 'Marine Master automatic professional 300m' text; steel hands; thick hand-applied indices | Navy blue sunburst: almost black indoors, bright sunburst in sunlight; gold seconds hand (lumed lollipop) and gold '300m' text; indices look applied but he hears they are stamped from the back; Prospex X on dial; ISO sliver/marking near 3 o'clock on post-March 2021 examples like his |
| date | – | Yes, at about 4:30 (date window with a sliver, per hOuORgMFkZ8) |
| movement | 8L35, 26 jewels, 28,800 vph, ~50 h power reserve, +10/-15 s/day (as stated, to verify) | Seiko 8L35B, 26 jewels, 28,800 vph, hacking and hand-winding, 50 h power reserve, based on the 9S55, about 192 parts, hand assembled at the Shizukuishi studio, MEMS escapement parts, SPRON springs; rated +15/-10 s/day, not regulated. His has run about +2 to +6 s/day across videos |
