Almost every watch has one metal. This one has two, and that changes the strap question completely.
The WHSA0012 is the Santos Skeleton in steel with an 18K yellow gold bezel — the gold ring carrying the eight signature screws, sitting around a steel case with a steel crown set with a faceted sapphire. Inside, the hand-wound calibre 9611 MC with its skeletonised bridges forming the Roman numerals, blued-steel sword hands, and an exhibition sapphire case back. Cartier sells this one on leather.
Which matters more than it sounds, because on the strap version the gold bezel is the only warm thing on the entire watch. There is no gold bracelet running down the wrist to keep it company. It is one warm ring, surrounded by cool steel, cool blued hands, and whatever you put underneath.
Get that underneath right and the two-tone looks deliberate. Get it wrong and the bezel looks like it wandered in from a different watch.
Lug Width: the WHSA0012 takes a 21 mm strap
On the product page, select the 21 mm option.
This is the large Santos, and the large takes a 21 mm strap. The medium, at 35.1 mm, takes 19 mm. That is the only sizing decision on the watch, and mixing the two up is the most common Santos ordering mistake there is.
| Santos model | Case | Strap |
|---|---|---|
| Large (WHSA0012) | Large case | 21 mm |
| Medium | 35.1 mm | 19 mm |
QuickSwitch
The factory strap uses Cartier's QuickSwitch system: press underneath the strap end and it releases. No tool, about ten seconds. Our Santos straps carry the same fitting — which is also why a generic 21 mm strap is not an option here. Without the QuickSwitch interface it has nothing to attach to.
The double folding buckle that came with the watch is worth keeping with the original strap rather than leaving loose in a drawer.
A strap for two metals
On a single-metal watch the strap only has to flatter one thing. Here it has to referee.
Cool and dark straps side with the steel. Black, grey and navy push the case towards its cool half, and the gold bezel becomes a deliberate accent — a bright ring framing a dark window. The skeletonisation reads sharply because the bridges have a dark background, and the watch looks technical rather than decorative.
Warm straps side with the gold. Brown and tan connect to the bezel instead of the case, so the gold stops being an outlier and becomes the theme. The two-tone effect gets stronger, not weaker, because the warm tone appears twice — once at the bezel, once at the wrist — instead of once and alone.
And one tone does neither, which is why Cartier picked it. The factory leather for this two-tone skeleton is a dark blue alligator, and blue is the only shade that manages both jobs at once: dark enough to back the bridges, cool enough not to fight the steel, saturated enough not to vanish underneath the gold. It is a more thought-through choice than the black most people would have expected.
All three are correct. What is not correct is choosing without noticing there were two metals to serve.
The four best straps for the WHSA0012
1. Brown leather — give the gold some company
Brown Leather Strap for Cartier Santos
This is the one most owners never try and the one that changes the watch most. With no gold bracelet on this configuration, the bezel is a single warm ring on an otherwise cool watch — and brown answers it. The gold reads as an intentional design decision rather than a lone flash of colour, and the whole piece warms up without losing the skeleton's clarity.
If the reason you chose the two-tone over the plain steel was the gold, wear it on this.
2. Blue leather — the factory answer, and the cleverest one
Blue Leather Strap for Cartier Santos
Cartier fits this watch with dark blue alligator, and once you understand the two-metal problem the logic is obvious: blue backs the bridges like black does, stays on the cool side with the steel, and has enough saturation of its own that the gold bezel does not overpower it. The hands are blued steel too, so the colour is already on the watch.
It is the balanced answer, and the safest strap here that still looks like a choice.
3. Black leather — for the movement
Black Leather Strap for Cartier Santos
Maximum separation. Black removes every competing tone from the wrist, which leaves exactly two metals in the picture — the steel case and the gold bezel — and puts the openworked movement in the sharpest possible relief. Every bridge edge and Roman numeral reads cleanly.
This is the most formal configuration, and the right one if what you care about is the calibre rather than the case.
4. Black rubber — the one you stop thinking about
Black Rubber Strap for Cartier Santos
Leather is the only thing this reference came with, which means it is also the only thing that wears out — and an openworked watch with an exhibition back is not something most owners want to be careless with. Rubber gives you a version you can wear without managing it: same dark background for the bridges, none of the care.
Our rubber straps carry a lifetime warranty, so it is a one-time purchase.
See every colour and material in the Cartier Santos QuickSwitch strap collection.
Fit, in one line
Order 21 mm with the QuickSwitch fitting, and click it in — no tools required.
More Cartier strap guides
- Cartier Santos de Cartier WSSA0018 Strap Guide — the large steel Santos, same 21 mm fit
- Cartier Santos de Cartier W2SA0016 Strap Guide — the two-tone medium, which takes 19 mm
- All Cartier strap guides
Leather is the only wearing part this watch has
Cartier supplied this configuration on a strap, with no metal bracelet to fall back on. That makes the strap the single component that will ever need replacing — and on a watch where the movement is the point, a tired strap is the only part that can make the whole thing look neglected.
Our Santos straps carry the QuickSwitch fitting in 19 mm and 21 mm, so they lock into the case the way the original does.
More than 50,000 customers worldwide, free shipping and free returns, and no import costs on any order, anywhere. Rubber straps carry a lifetime warranty; leather is covered for one year.
