Apple CEO Tim Cook wears his Apple Watch everywhere (even in the shower). But if you look closely at photos of his watch, you can see that it's a totally unique model that is not available to the public.

Take a look at the photo of Cook holding an Apple Watch at the top of this article. Notice anything weird about the one he's wearing on his left wrist?

Let's take a closer look:

Cook wears a stainless steel Apple Watch with a white sport band. That's not the unusual bit. What's different about Cook's watch is the digital crown (the circular button that sticks out). Cook's crown is capped with a section that's coloured red.

You can't buy the stainless steel Apple Watch with the red crown like Cook's — Apple simply doesn't sell that type of watch. Instead, only the gold Apple Watch Edition watches come with coloured crowns — and they start at £8,000 ($12,269).

The gold Apple Watch features a red crown. Apple

So it looks like Cook is wearing a custom model of Apple Watch with a unique digital crown, possibly an early test model that he has decided to stick with.