A 21 mm Strap for the Santos QuickSwitch Lug
Cartier builds the Santos de Cartier Medium (WSSA0010) and the Santos de Cartier Large (WSSA0009) around the same QuickSwitch lug, so one strap shape covers both watches. This one is cut to that lug rather than adapted from a universal band: the ends are shaped to meet the case squarely, the quick-release bar sits inside the strap, and the release button already built into the case does the rest.
Two materials cover two ways of wearing it. FKM fluororubber is the dense, matte one: sweat, sun, heat and everyday chemicals leave it alone, it keeps its shape instead of hardening with age, and a wipe brings it back clean. Nylon canvas is the lighter option, woven and breathable, and it dries quickly after a swim or a hot afternoon. Both are water-resistant, and both are made to close on the Cartier folding clasp already on your watch.
One for the weekday and one for the heat is the usual setup, though plenty of owners keep both. If you look after several Santos watches — a shop counter, a repair bench, a second watch at home — we can arrange custom fluororubber material watch straps to order; tell us which references you are fitting and we will confirm the details.
FKM Rubber Against Nylon Canvas
| How it feels | Soft, dense and matte against the skin | Light and woven, with a texture you can feel |
| Water and sweat | Does not take on water — rinse it and wear it again | Water runs off; dries quickly once off the wrist |
| Hot weather | Warmer on the wrist on the hottest days | Lets air through, the cooler of the two |
| Everyday exposure | Sun, heat and everyday chemicals do not harden it | Hand-washable; resists stains and odour |
| Well suited to | Swimming, training, daily wear, the office | Summer, travel, humid climates, weekends |
| Shades offered | The full six-shade FKM range | A shorter set that includes black, green and camo |
Measurements at a Glance
| Specification | Detail |
|---|
| Fits | Cartier Santos de Cartier WSSA0010 (Medium, 35.1 mm) and WSSA0009 (Large, 39.8 mm) |
| Lug width | 21 mm QuickSwitch |
| Widths listed | 19 mm and 21 mm |
| Strap sections | 110 mm + 80 mm |
| Thickness | 2 mm |
| Weight | 14 g |
| Materials | FKM fluororubber or nylon canvas |
| Fitting | Quick-release bar built into the strap; no tools needed |
| Clasp | Works with the original 18 mm Cartier folding clasp |
| Colours | Black, dark blue, sky blue, white gray, white, yellow |
| Water resistance | Suited to the 100 m rating of the Santos case |
What Arrives, and What You Keep
One strap arrives, with its quick-release bar already fitted and both ends finished — there is nothing to assemble before it goes on the watch.
This is an aftermarket part made for the Santos, not a Cartier original, and it is not connected with or endorsed by Cartier. What we can tell you plainly is how it fits: the ends are cut for the QuickSwitch lug, they sit level with the case once the bar is fully home, and the strap meets the original clasp at the buckle end. If your watch is not one of the two references, say so before you order and we will check it.
The dimensions are fixed by the case. Colour is the one thing with room to move, and a custom fluororubber material watch strap can often be arranged for a shade that is not stocked — send us what you are matching and we will confirm what is possible.
Technical Support & Model Matching
FUERMAN has been supplying watch parts and accessories from Huadu District, Guangzhou since 2010 — 15+ years in the trade, a 60-strong team and a deep ready stock held in China. Our technical team, which includes technicians with 30+ years of watchmaking experience, matches items to your watch by brand, model or reference number before you order, so you know it will fit. Send a photo or a measurement if you are unsure: we will confirm the right choice, talk you through fitting, and stay with you afterwards — troubleshooting, replacement parts and after-sales help long after your order arrives.
FAQ
Q1. Does one strap fit both the Santos Medium and the Santos Large?
Yes — WSSA0010 (Medium) and WSSA0009 (Large) share the same QuickSwitch lug, so the same strap covers either watch. The reference is engraved on the case back; if it matches one of those two numbers, the fit is confirmed.
Q2. How does FKM fluororubber compare with nylon canvas day to day?
FKM is the denser, matte material: it does not absorb sweat or water, it resists sun and heat, and it stays soft instead of hardening with age. Nylon canvas is lighter and lets air through, which most owners notice first in a humid summer, and it dries quickly after a swim. For swimming, training and general daily wear, FKM is the safer default; in hot, dry conditions the woven version feels cooler.
Q3. Does the strap come with a new clasp?
No. It is made to take the original 18 mm Cartier folding clasp that is already on the watch, so the clasp moves across when you change straps and there is no new hardware to buy. The strap itself arrives with its quick-release bar in place, ready to press into the case.
Q4. How does the QuickSwitch release work?
A small button sits on the underside of each lug. Press it and the quick-release bar retracts so the strap end slides free of the case; let go and the bar springs back out. Fitting is the same action in reverse — line the bar up with the opening in the case and press the end in until it clicks. No spring bar tool is involved at any point, which is why nothing sharp ever comes near the watch.
Q5. Will the rubber harden or turn shiny with age?
That is exactly what FKM is chosen to avoid. Ordinary rubber and cheaper silicone harden, crack and go glossy as they age; FKM fluororubber keeps its softness and its matte surface, and sweat, sun, heat and everyday chemicals do not trouble it. Rinse it after heavy wear and it should look the same after a season as it did on the first day.
Q6. Which material should I start with?
Start with FKM fluororubber unless you specifically want the lighter feel — it covers swimming, the office and daily wear without needing much looking after. Buying a watch strap online means you cannot feel either material first, so it helps to think about the season you wear the watch most: if your summers are hot and humid, the nylon canvas is the one that feels cooler, and plenty of owners end up with both.
Q7. Can I get a colour that is not in the list?
The stocked FKM shades are black, dark blue, sky blue, white gray, white and yellow, and the nylon canvas range is shorter. If none of them matches what you have in mind, tell us what you are matching — a dial, a leather you already wear, a team colour — and we will confirm whether a custom fluororubber material watch strap can be arranged before you order.
