U1 vs SLA023
Geth put them head to head in "Seiko SLA023 VS Sinn U1 Tegimented. 2.8k diver battle". Scores, specs and verdicts side by side.
Sinn U1 Tegimented (full Tegiment)
The most legible watch he's ever seen: invisible crystal, Lego hands and near-unscratchable submarine steel. Bezel and clasp grated at first, but it went on to become his favourite watch, level with his SLA023.
Seiko SLA023 Marinemaster 300
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.
Too close to call
I couldn't decide. The Sinn wins on anti-reflective, the bracelet screws and toughness, the Seiko wins on lume, on-the-fly adjustment and that zaratsu design language. Neither one is wrong: I absolutely love both of these pieces.
Spec sheets
| U1 | SLA023 | |
|---|---|---|
| case diameter (mm) | 44 | 44.3 |
| thickness (mm) | 14.7 | 15.4 |
| lug to lug (mm) | 50.4 | 50 |
| lug width (mm) | 22 | 20 |
| weight (g) | 222 g with all links stated by gethin | 222 g with all links (about 205 g with a link out each side), said of both MM300s stated by gethin |
| case material | German submarine steel (he says from ThyssenKrupp Marine Systems, used for U-boat hulls), fully Tegimented and bead blasted; surface hardness 1,200-1,500 Vickers (vs about 220 for 316L); totally non-magnetic, seawater resistant | 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 | Sapphire, AR-coated top and bottom ('double AR') | Flat sapphire with an internal dome (AR coating inside) |
| water resistance (m) | 1000 | 300 |
| crown | 7 mm, signed, screw-down | Screw-down, signed (laser-etched 'Prospex X'), at 4 o'clock |
| caseback | Screw-down, with Tegiment logo | Monocoque, no removable caseback; tsunami wave on the back. Not limited. His is a March 2021 J1 |
| bezel | Captive (screwed on), 60-click unidirectional, Tegimented, 'mission timer' bezel | 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 | Matte black, deep-dished; thick 'Lego/Roblox' hands; syringe-tipped markers; 60-minute/seconds track; red 'U1 Automatik' text, 'made in Germany', 1000 m on dial | 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 | Yes, at about 4:30 (date window with a sliver, per hOuORgMFkZ8) |
| movement | Sellita SW200-1, 26 jewels, 28,800 vph, 38 h power reserve, hacking and hand-winding, regulated by Sinn. This example: +6 s in 6 days on a winder | 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 |
