No watch family gets re-strapped more than a Seiko diver. The SKX007 is the most owned mechanical dive watch in the world and the one most associated with the strap-changing hobby — owners routinely keep more straps for it than for anything else in the box. The Turtle, the Samurai and the Sumo get the same treatment.
There's one reason people get it wrong, and it's worth knowing before you order.
Which Strap Size Fits Your Seiko?
Seiko uses two widths across almost the whole modern diver range — and, mercifully, no half sizes anywhere:
22 mm
- SKX007 / SKX009
- Prospex Turtle (SRP777, SRPE93 and the King Turtle)
- Prospex Samurai (SRPB51, SRPB99)
- Seiko 5 Sports SRPD
20 mm
- Prospex Sumo (SBDC001, SPB101)
- SKX013
- Prospex SPB143 / 62MAS
- Captain Willard
- Alpinist
- SARB033 / SARB035 and most Presage
The Sumo is the single most common Seiko sizing mistake. It's a 45 mm dive watch sitting in a family of 22 mm divers, and it takes 20 mm. On paper that looks wrong — most 45 mm divers use 22 mm or wider — but the Sumo's curved lugs are designed for it, and a 22 mm strap simply will not go in. The SKX013 is the runner-up: it looks like an SKX, and it's 20 mm too.
If your model isn't listed — a Tuna, a vintage Seiko 5, or one of the older Monster references — pop the strap off and measure between the lugs before ordering. It takes ten seconds and it's the only way to be certain.
The Best Part: One Strap Fits Several Watches
Here's what makes Seiko different from every luxury brand. Most makers force you to buy per model. Seiko largely doesn't — the SKX007, the Turtle, the Samurai and the Seiko 5 SRPD all share 22 mm. If you own two or three of them, one strap covers the lot, and swapping between them costs nothing.
That changes the question from "what strap suits my SKX" to "what does my Seiko shelf need". Which is exactly how most owners end up shopping anyway.
The Best Upgrades for a Seiko Prospex
1. Oyster Bracelet – The Straight Upgrade
The single biggest visual improvement you can make to a Seiko diver is a proper solid-link bracelet, and the Oyster bracelet for Seiko is the obvious first move — brushed three-link steel, a secure clasp, and a clean sporty profile that suits a dive case perfectly. Available across 18–26 mm, so it covers both the 20 mm and 22 mm sides of the range.
2. Jubilee Bracelet – The Classic Seiko Move
Putting a five-link Jubilee bracelet on an SKX is one of the most popular upgrades in the entire watch hobby, and for good reason: the mix of polished and brushed links adds a richness the standard bracelet never had, and the finer links wrap the wrist more comfortably. It's the combination that makes a Seiko diver look like a far more expensive watch.
3. Presidential Bracelet – The Bold One
The three-piece Presidential bracelet is the dressiest of the three — solid, substantial and unmistakably luxury in feel. It's the one for a Seiko 5 or a Presage rather than a hard-use diver, and it transforms the character of the watch completely.
4. FKM Rubber – For the Water
A dive watch should have a rubber strap in the drawer. Our straight-end FKM rubber straps come in 20 mm, 22 mm and 24 mm — both Seiko sizes covered — and FKM is the material worth insisting on: it doesn't chalk, doesn't hold odour, and shrugs off salt water and sunscreen. Black is the safe answer; orange on a black-dial SKX is the most celebrated Seiko strap combination there is, and it's the correct colour for a dive watch besides. Every rubber strap carries our lifetime warranty.
For Turtle and Sumo owners, one extra note: those cushion cases curve straight into the lug, so a curved-end rubber strap continues the line of the case where a straight cut interrupts it. Available in 18–22 mm.
Changing It Is Easier Than on Any Other Watch
The SKX007 and SKX009 have drilled through-lugs — the holes go all the way through the lug, so you push the spring bar out from the outside instead of fishing around inside the case. It's the easiest watch in any collection to re-strap and the hardest to scratch while doing it. A Seiko installation tool makes it a one-minute job.
Why Seiko Owners Choose Helvetus
Helvetus is one of the leading names in aftermarket straps and bracelets for watches: proper materials, honest sizing advice, and a range that covers the odd widths as well as the common ones. Rubber straps carry a lifetime warranty, steel bracelets and other materials a one-year warranty, shipping is free worldwide, and there are no import costs on any order — part of why more than 50,000 customers have trusted us with their watches.
Browse the Seiko collection to find your bracelet, and remember to check whether you're a 20 or a 22 before you order.
