Many may have missed an interesting moment at this year’s iPad Pro and iPad Air launch — Apple CEO Tim Cook was seen in a special pair of sneakers. He laced up a one-of-one Air Max 1 ’86 that was created by Nike for Cook on an iPad Pro with the brand’s first-ever Apple Pencil Pro.

The shoes featured an off-white mesh body and sole, while the mudguard and toe included a unique soft “wave” effect and a rainbow-speckled pattern. On the tongue, there’s a handwritten “made on iPad” and the iconic swoosh features a rainbow stitching that looks like it was drawn with an Apple Pencil Pro.

Cook, a Nike board member since 2005, became the lead independent director of the board in 2016. Nike and Apple have a friendly relationship and have worked together on products, starting with Nike+ Running.

So, to see Cook wearing something special on his feet was a nice bit of brand synergy, but you won’t be able to buy a pair as they’re a one-off.