The Nike Air Foamposite One, one of the boldest and strangest sneakers of all time, is turning 20 this year. As part of its ongoing celebration of the shoe in 2017, Nike released a history lesson on its design today that includes some interesting sketches and early samples.

The coolest among them is the above, a Nike Air Foamposite One featuring a Max Air bubble on the heel. That cushioning system was eventually swapped out in favor of a full-length Zoom Air set-up with double stacked bags in the heel.

Nike designer Eric Avar, who is largely credited with creating the Foamposite line, says it took three to four years to make the shoe a reality.

Also celebrating the model's 20th anniversary is a retro of the original "Royal" colorway releasing on Jan. 20.

Read more about the creation of the first Foamposite shoe via Nike here.

Nike Foamposite Sketch
Image via Nike
Nike Foamposite Design Sketch
Image via Nike
Nike Foamposite Sample
Image via Nike