Replacement FKM Rubber Strap for Cartier Santos WSSA0009 – QuickSwitch System

Product Overview

This is a replacement rubber strap cut for the Cartier Santos large — the 39.8 mm case that runs the original QuickSwitch system, reference WSSA0009. It goes on where the original leather band has cracked at the lugs or gone dark at the edges, or where the steel bracelet starts to feel heavy by the end of a working day, and it turns the same square case into something you can wear with a T-shirt as easily as with a shirt cuff.

The ends are shaped to the Santos lug geometry rather than left flat, so the strap meets the case the way the original part does, with no step and no gap left showing between strap and case. The two halves are cut 115 mm and 90 mm, the proportions the large Santos uses, and the whole strap weighs 23 g, which keeps the watch light on the wrist. Because it is a fluororubber material watch strap rather than leather, sweat and rain do not stiffen it or stain it the way a leather band darkens after one wet summer.

Colours run from black and deep blue through royal blue and orange to white. Black keeps the rubber quiet against the dial; orange and white make it the loudest thing on the watch. The strap narrows towards the tail, which is what lets you keep the original 18 mm Cartier deployant clasp instead of buying new hardware.

One thing worth being clear about before you order: this is an aftermarket replacement part made by Fuerman, not a Cartier product. The watch in the photographs is there to show how the strap sits on the case, and it is not included with your order.

Colour & Clasp Options

• Five strap colours. Black, deep blue, royal blue, orange and white. Black does the most to hide everyday marks and suits almost any dial; deep blue is the closest match to Cartier's own dark dials; royal blue is a brighter, more modern blue; orange is the sporty choice for anyone who wears the Santos as a rubber-strap watch; white is the crispest and looks sharpest on a steel case.
• Match the hardware to the case. The buckled options come with a folding clasp in silver, gold or rose gold. Silver belongs on a steel Santos; gold and rose gold are the natural pairing on a two-tone or gold model.
• Or take it with no buckle. If you plan to keep the clasp that came with the watch, choose the no-buckle option — the tail is cut to thread through the original 18 mm deployant clasp.
• How the finish looks. The rubber has a smooth, low-sheen surface rather than a glossy one, and the metalwork on the buckled options is polished, so the strap reads as a considered upgrade rather than a plain band.
• Colour on screen. Product colours can look slightly different depending on your monitor or phone display, so treat the photographs as a close guide rather than an exact match.
• A second colour for the weekend. Because the ends click in and out, a spare strap in another colour is an easy way to change the whole character of one watch.
• Nothing here quite right? Tell us what you have in mind and we can talk through custom fluororubber material watch straps — another shade, another hardware combination, or a set for more than one watch.

Specifications

Sizing & Fit

1. Confirm the model first. This strap is cut for the large Santos with the 39.8 mm case and the original QuickSwitch fitting. If your Santos is the medium version, this is not the strap for it — tell us and we will point you towards the right one.
2. Check the lug gap. The large Santos runs a 21 mm gap between the lugs, and that is the size to order. A 19 mm version is also listed, so choose that only if you have measured your own gap and it comes in at 19 mm.
3. Think about length as well as width. This custom fluororubber material watch strap is cut 115 mm on one half and 90 mm on the other, so the clasp lands where it does on the strap you are replacing. Most adult wrists sit comfortably inside that with the clasp on a middle hole; if you wear unusually large or small watches, say so when you order and we will check it with you.
4. Measure with the old strap off. Take the strap off the lugs, lay a ruler flat across the gap and read the distance between the inside faces of the two lugs. That number is the width you need — not the width of the old strap where it meets the buckle, which is narrower.
5. Expect a taper. The strap narrows towards the tail so the 18 mm clasp that came with your watch fits. That is deliberate: it keeps your original buckle usable and gives the watch the slimmer profile it has on the wrist.
6. Understand the thickness. The strap runs 1–3 mm through its length, thin at the lug ends so it tucks under the case cleanly and slightly fuller through the middle so it does not twist or bunch when you fasten it.
7. Still unsure? Send a photograph of the watch with the strap off, or the reference from the caseback, and we will confirm the size before anything is packed for you.

FKM Fluororubber Material

Material is the part a photograph cannot show, and it is the main reason people hesitate to buy a watch strap online: two black straps look identical on a screen and behave nothing alike on a wrist. FKM — fluorine rubber — is the compound used here, and it is a genuine step up from the silicone and natural rubber most replacement straps are cut from.

FKM resists sweat, salt water, sun and heat far better than ordinary rubber. That matters on a Santos, because a watch like this goes to the office, on holiday and to the gym, and the strap is the part that takes all of it. Natural rubber hardens and cracks over time and softer compounds can cling and squeak; FKM stays supple and keeps a clean, matte surface that does not collect dust the way tackier rubbers do. The strap itself is happy in water — how water-resistant your watch is depends on its seals and case, not on the strap.

It is also easy on skin. There is no stiff backing and no sharp edge at the lug end, so it sits quietly on the wrist through a long day, and it does not develop the rubber smell that some cheaper bands pick up after a few weeks in the heat.

Looking after it takes a minute. Rinse the strap in fresh water after swimming or a heavy workout, wipe it with a little mild soap if it starts to look dull, dry it with a cloth, and store the watch flat rather than folded in a drawer. There is nothing to oil or treat — it is rubber, not leather, and it does not need conditioning.

Fitting With QuickSwitch

1. Work over a soft surface. Take the watch off and lay it face down on a cloth or in a tray, so nothing gets scratched if a part slips out of your fingers.
2. Release the old strap. Press the QuickSwitch button at the lug and slide that strap end out of the case. Do one side at a time so the other end is always holding the watch.
3. Press the new end in. Line the replacement end up with the lug, push it in and let the mechanism seat. You should feel it settle rather than have to force it — if it will not go in, pull it out, look at the alignment and try again.
4. Check both ends. Give each end a gentle tug. A correctly seated end has no movement in it and sits level with the case, which is what keeps the strap looking flush from above.
5. Keep or change the clasp. This custom fluororubber material watch strap narrows to 18 mm at the tail, so your original Cartier deployant clasp threads straight on. If you ordered a buckled option instead, fit the folding clasp that came with it.
6. Clasp changes want a small tool. The QuickSwitch ends need nothing at all, but moving a spring bar between two clasps is easier with a short-nose spring bar tool. Some options include a fitting tool and some do not, so confirm that when you order.
7. Give it a day before you decide on the hole. FKM has a little give to it, so the strap moulds to the wrist over the first day or two rather than sitting rigid from the first wear.

Other Straps In The Range

Ordering & Confirmation

• Send the watch details with your order. The reference from your caseback and the width you measured, so the strap can be checked against your watch before it is packed.
• Settle the clasp question first. If you are keeping your original Cartier clasp, choose a no-buckle option; if you want a folding clasp, pick silver, gold or rose gold to suit the case.
• Ask what the option includes. Some options come with a fitting tool and some do not — confirm the contents of the exact option you are buying.
• Something not in the list? We can discuss custom fluororubber material watch straps for other colours, widths or watches; send a photograph or a reference and we will tell you what is possible.
• Availability and timing. Confirm current stock, dispatch timing and delivery arrangements with your sales contact when you place the order, particularly if you need the strap by a particular date.
• Packing and presentation. Ask about protective packing for the strap and hardware, and about gift packing or combined packing if this is a present or part of a bigger order.
• Check it the day it arrives. Lay the strap against the lugs before you wear it. If anything looks off, get in touch before fitting the second side — it is much easier to sort out while the strap is still unused.
• Owner feedback. The ratings and buyer photographs on our strap listings are worth a look if you are torn between two colours, because they show the strap on a real wrist rather than on a studio background.

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