Short answer: a Cartier Tank Must small "replica" with a leather strap is an unlicensed copy of a trademarked watch. In the US it is illegal to import for resale and illegal to sell, and the shortcuts show up fast in the dial printing, the case edges, and the strap hardware. If you want that look on your wrist, the real options are a genuine Tank Must small, a pre-owned one, or a rectangular watch from a brand that actually sells what it makes.
What the genuine Tank Must small actually is
Cartier's Tank Must small is a steel rectangle measuring about 29.5 mm by 22 mm, thin enough to slip under a cuff, with a quartz movement, a sapphire crystal, and a leather strap on a pin buckle. The case has a stepped profile and a crown topped with a blue spinel cabochon. Cartier rates the quartz movement for roughly eight years of battery life. That spec sheet is the benchmark, because it is what every copy is trying to imitate from photos.
The legal reality in the US
Cartier owns the Tank shape and name as registered trademarks. Selling counterfeits is trafficking in counterfeit goods under 18 U.S.C. 2320, which carries prison time on a first offense. US Customs and Border Protection can seize and destroy shipments, and repeat importers face civil penalties per item. There is a narrow allowance for a single item of a type brought in for personal use, and people quote it constantly, but it does not make the sale itself legal and it does not protect a package from being stopped.
Where the copies give themselves away
Movement aside, a counterfeit is usually caught out by details:
- Dial printing that looks bold or blurry, with the Cartier signature too heavy and the minute track uneven
- Case sides that are polished where the original is brushed, or sharp edges where the original is softened
- A cabochon that is glassy plastic rather than a smooth blue dome set flush in the crown
- Strap stitching that runs crooked, with hardware that feels light and plates instead of solid steel
- Caseback engraving that is stamped shallow, with wrong reference numbers or odd spacing
Better ways to get the look
A genuine steel Tank Must small on leather lists in the low thousands of dollars, and pre-owned examples trade below retail, which surprises people who assume Cartier means five figures. If the budget is tighter, rectangular homages exist from mainstream makers: Seiko's rectangular Essentials line and the Hamilton Ardmore both sit in the low hundreds, keep a classic tank silhouette, and come with service and warranty support. Vintage dress watches from Longines, Omega, and Bulova also fill the same niche for similar money.
The honest trade-off
Copies are cheap for a reason. Nobody services them, parts do not exist, water resistance claims are usually fiction, and resale value is close to zero. A $250 homage that runs for a decade beats a $120 copy that stops in month nine. If the point is owning a Cartier, save for the real one or buy pre-owned with papers. If the point is wearing a rectangle, buy a rectangle from a company that will still be around when the battery dies.