With a starting price of £15,850 (around $21,000), the Senturion Key S177 costs more than some cars.
With prices rising to almost £100,000 ($130,000) depending on your configuration, it can cost more than most cars.
No surprise it almost exclusively adorns the wrists of billionaires, high flying celebrities and footballers.
Excessive? Sure. But there's more to this ostentatious piece of jewelry than meets the eye.
The wearable Faraday cage
Each Senturion Key is crafted from precious materials and, if the customer wishes, laid with a host of diamonds or similar exclusive stones.
The customer's configuration of metals and stones determines the final price which, as I've already mentioned, can go very, very high.
Why is it called the S177? Because just 177 units are being made, ensuring it remains an exclusive item. While it is limited, it's actually one of Senturion's larger runs, with some previous series limited to just 7 or 8 keys in total.
The process of making a key compatible with your supercar isn't a straightforward one. Owners need to hand over the spare key to their vehicle for Senturion to deconstruct.
It then creates its own osydian boards that replicate the circuitry in the key, but on a much smaller scale.
This allows the board, which uses RFID technology to communicate with the car, to be embedded into the wearable.
That's not the end of the story however. With a generous amount of metal used in each wearable key, Senturion discovered another roadblock. Connectivity.
Metal blocks RF signals, so getting the exclusive keys to actually talk to cars required some creative thinking.
Metal: Rose Gold
Talon insert: Rose Gold
Middle insert: Black Carbon
Etching: Baby Blue
Price: £34,050 (around $45,000)
Senturion Director, Ayla Varquin told us how the company managed to work around the problem.
"As RFID signals are routinely blocked by metals (hence why conventional keys are largely made of plastic), the alien shaped frame of the Senturion Key is designed to act as a 'Faraday Cage'," she explained "whilst also incorporating flexible omni-directional antennas in the straps."
The result is a wearable key that actually has a bigger working range than the spare key handed over at the start of the process.
The extended range is only a few meters, but it's an impressive feat and one Senturion has been first to do. It's even applied for a global patent for the technology, such is its complexity.
The battery is also located in the strap and, Senturion says, can last for up to six years.
Each key is hand crafted and polished in the south of England, and each one takes between two and three weeks to complete depending on the complexity of the customer's composition.
It is possible to change the car the Senturion S177 is assigned too, but the process involves sending the wearable back to the firm along with the spare of your new vehicle. The process to swap cars takes around a week and will set you back £1,600.
Does it work?
Fear not, I made sure I thoroughly tested the S177. It's a hard life, but that's what I do.
I took it upon myself to slide into the seat of a bright green Lamborghini Aventador SV in London's Mayfair for a scenic drive around Hyde Park to ensure it lives up to the promise.
Lamborghini Aventador SV
Top speed: 217mph
0-62mph: 2.8 seconds
Price: from £315,000 (around $420,000)
Image credit: HyperBahn
Approaching the car, a single click of the button on the top of the S177 unlocks the Lambo. Once inside the RFID technology works just like any other keyless ignition key. Place your foot on the brake and hit the Start/Stop button.
When your drive is over, exit the car and a double click of the button on the S177 locks the vehicle.
The Senturion S177 isn't small, nor is it understated, but considering its size and the materials it's crafted from I was surprised by just how comfortable it was to wear.
After a few minutes of wearing it while driving I had forgotten it was on my wrist. It doesn't get in the way, and it doesn't feel like it's weighing your arm down.
I had removed my watch for the S177 to take pride of place on my wrist, because it doesn't feel like an item you can really wear alongside a traditional timepiece.
A couple of times during my test drive I attempted to check the time - only to be met with the wearable key. Perhaps for its next series Senturion may consider adding a clock?
The Senturion S177 is expensive, exclusive and some will argue unnecessary, but that's sort of the point.
It's an item for the few, not the many, and while people will question the design and price tag, this wearable key for your supercar can still boast an impressive piece of technology at its heart.
- John McCann is getting behind the wheel to give you an alternative look at the wealth of cars – and the tech inside them – available today. From super-fast sports cars to tech-packed hatchbacks, he'll take you through a range of makes, models, power and price tags in his regular TR Drives column.