2026-05-07
Best Watch Straps for the Seiko Prospex SPB317
Best Watch Straps for the Seiko Prospex SPB317
The Seiko Prospex SPB317 is a reinterpretation of one of the most historically significant dive watches Seiko ever produced — and one with a specific and unusual cultural legacy. The original 6105-8000 was introduced in 1968 as the successor to the 62MAS, Seiko's first professional diver. The 6105 took the 62MAS's round case and transformed it into something more architecturally distinctive: a cushion-shaped case with a recessed, asymmetric crown at 4 o'clock, a more compact bezel, and a cleaner dial layout. It was a watch that looked more refined than the dive watches of its era while retaining complete operational capability.
The 6105 appeared on the wrists of American servicemen during the Vietnam War — not issued equipment, but personally purchased watches brought to the conflict. Most famously, the asymmetric sibling the 6105-8110 appeared on the wrist of Martin Sheen in Francis Ford Coppola's Apocalypse Now, earning it the lasting nickname the "Willard" after Sheen's character. The symmetric 6105-8000 that the SPB317 reinterprets shares this cultural moment — the same case design, the same era, the same world.
Worn & Wound's reviewer described the SPB317 as finding "a spot right alongside my 7002-700A and SPB149" — high praise from a collector who owns the most celebrated Seiko references. The SPB317 resolves the tension between vintage character and modern specification more naturally than most Seiko reinterpretations: it looks vintage at a glance but wears with the 12.3mm thinness and 200m water resistance of a genuinely modern diver.
Seiko SPB317 Strap Size
The Seiko Prospex SPB317 uses 20mm lugs — confirmed by Seiko's own specifications and StrapSeeker's measurements. 41mm case, 12.3mm thick, 46.9mm lug-to-lug. Calibre 6R35, 70-hour power reserve.
SPB313 (blue dial, bracelet) — 20mm. SPB315 (green dial, bracelet) — 20mm. SPB317 (black dial, rubber strap) — 20mm.
All three references share the same 20mm lug width. The SPB317 ships on rubber only — no bracelet option for the black dial. The SPB313 and SPB315 ship on bracelet.
The 1968 Cushion Case — Character and Strap Logic
The SPB317's cushion case is its defining visual element. The soft square outline — neither round like the SKX nor barrel-shaped like the Turtle — creates a silhouette that is immediately distinctive and immediately vintage. Worn & Wound described the matte black dial as pairing "beautifully with a neutral tone fabric strap" — a specific recommendation from direct experience that validates olive and grey nylon as the most natural SPB317 fabric choices.
The Vietnam War and Apocalypse Now cultural context creates a specific strap heritage logic. The servicemen who wore the 6105 in the field wore it on whatever was available — operational nylon, basic rubber, worn leather. Straps that reference this operational world are the most historically coherent choices for the SPB317.
Best Rubber Straps for the Seiko SPB317
Tropical style FKM in black at 20mm — the most historically resonant and most collector-celebrated SPB317 combination. The vintage basket-weave and honeycomb surface patterns reference the late 1960s tropical rubber of the original 6105-8000 era. A watch designed in 1968 on vintage-textured rubber from the same era creates the most period-coherent active combination available.
Brown tropical FKM at 20mm — for the most aged and most specifically vintage combination. The warm brown tropical rubber mimics the oxidation of original 1960s dive watch rubber. On the SPB317's matte black dial, warm brown creates a temperature contrast that reads as deliberately vintage.
Classic FKM rubber in black at 20mm — the most practical active choice. The SPB317's 200m water resistance makes black FKM appropriate for any active use. Seiko ships the SPB317 on rubber as standard, validating rubber as the factory-endorsed choice.
Grey FKM rubber at 20mm — for the most tonal combination with the matte black dial.
Best Nylon Straps for the Seiko SPB317
Worn & Wound specifically recommended "neutral tone fabric" as the most natural SPB317 strap pairing — olive, grey, and khaki nylon suit the matte black dial's own earthy, neutral character.
Single-pass nylon — Original at 20mm with the CNS solid buckle. Most appropriate SPB317 colourways:
- Olive / khaki — the most specifically 1968 military-operational aesthetic. The Vietnam War context makes olive nylon the most historically coherent fabric choice for this specific watch.
- Black — the most minimal.
- Admiralty Grey — for the most composed neutral combination that Worn & Wound specifically identified as the most natural pairing.
- Black and grey — the most understated collector combination.
Canvas at 20mm in olive or khaki — the most specifically field-operational fabric for the SPB317's Vietnam era heritage.
Marine Nationale elastic at 20mm — the most comfortable SPB317 daily wear option. Navy or black.
RAF single-pass nylon at 20mm — for the most specifically military heritage fabric combination.
Paratrooper elastic at 20mm — the most comfortable daily option.
Best Leather Straps for the Seiko SPB317
Brown vintage two-stitch calfskin at 20mm — the most historically resonant SPB317 leather combination. The warm brown and two-stitch construction reference the 1968 era of the original 6105-8000 directly. On the matte black dial, warm brown creates a temperature contrast that reads as specifically period-correct.
Dark brown padded calfskin at 20mm — the most substantial everyday leather for the SPB317's 12.3mm case thickness.
Classic black calfskin at 20mm — the most formal SPB317 combination.
Tan suede at 20mm — the most relaxed leather option.
Dark brown suede at 20mm — for smart-casual and weekend contexts.
The Seiko 1968 Line — SPB313, SPB315, SPB317
All three references share the same case, movement, and 20mm lug width:
SPB313 — blue dial. Brown vintage two-stitch leather for warmth against the blue dial; navy nylon for tonal coherence; black tropical FKM for collector active.
SPB315 — green dial. Olive canvas for the most coherent military-operational combination; brown vintage two-stitch leather for warm contrast.
SPB317 — black dial. Olive single-pass nylon following Worn & Wound's neutral tone recommendation; black tropical FKM for vintage active; brown vintage two-stitch leather for characterful dress-sport.
All at 20mm.
The Seiko Prospex Cluster
CNS now covers the primary Seiko Prospex references:
Seiko Turtle — 22mm.
Seiko SPB143 / 1959 Alpinist — 20mm.
Seiko Prospex Speedtimer — 20mm.
Seiko SPB317 / 1968 6105 — 20mm.
Recommended Combinations
Most historically resonant — black tropical FKM at 20mm — 1968 era vintage rubber.
Most specifically vintage military — olive canvas at 20mm — Vietnam era operational equipment.
Most reviewer-validated — olive or grey single-pass nylon at 20mm — following Worn & Wound's neutral tone recommendation.
Most characterful leather — brown vintage two-stitch calfskin at 20mm — 1968 era leather against matte black dial.
Most comfortable daily — Marine Nationale elastic at 20mm.
Frequently Asked Questions
What size strap does the Seiko SPB317 take? 20mm — confirmed by Seiko's own specifications. All three 6105 reinterpretation references (SPB313, SPB315, SPB317) share the same 20mm lug width.
What is the best strap for the Seiko SPB317? Black tropical style FKM at 20mm for the most period-coherent active combination — vintage rubber on a 1968-era design. Olive single-pass nylon following Worn & Wound's neutral tone fabric recommendation. Brown vintage two-stitch leather for the most characterful dress-sport transformation.
What is the difference between the SPB317 and the Captain Willard SPB151? Both reference the 6105 family but from different angles. The SPB317 reinterprets the symmetric 6105-8000 in a slimmer, more modern execution at 12.3mm thick. The Captain Willard SPB151/SPB153 reissues the asymmetric 6105-8110 — the "Willard" from Apocalypse Now — with its distinctive asymmetric crown guard. Both use 20mm lugs.
Why is the SPB317 called the "Slim Turtle"? The SPB317's cushion case shape references the Seiko Turtle's own cushion case family, but at 12.3mm thick versus the Turtle's 13-14mm the SPB317 is meaningfully slimmer. The "Slim Turtle" nickname reflects both the case shape connection and the profile difference — a more elegant, less massive presence on the wrist.
All CNS straps for the Seiko Prospex SPB317 are available at 20mm. Standard delivery worldwide. 30-day returns.