Tomorrow is Nike Air Max Day! So today, technically, is Nike Air Max Day Eve.

In the absence of a Nike-themed advent calendar, consider these five facts, that make the Nike air bubble so iconic, one final ‘fun-size’ treat ahead of the main event tomorrow.

1. The ‘air’ used in the cushioning of Nike Air Max isn’t air at all. In fact, it’s everyone’s favourite element, Nitrogen. Cool story, bro.

2. Shoe designer (and owner of, arguably, the world’s best name) Tinker Hatfield took his inspiration for the original Nike Air Max from The Pompidou Centre – an art gallery in Paris, famous for its “inside out” design. He wanted to make the inner-workings of the air cushioning visible for all to see.

3. The nerdier Nike Air Max fans among you might be interested to know that the air pressure inside a Nike air bubble is typically 25 PSI, or ‘pounds per square inch’. That’s a similar level to the pressure inside the average car tyre.

4. The people who came up with the air cushioning technology showed it to a number of different footwear brands. Thankfully, it was Nike who realised its potential, promptly snapping it up and seamlessly integrating it into its new range of running shoes 27 years ago.

5. The air bubble is made of polyurethane, which is also used to coat US Navy ships to protect them from damage at sea.