The model officially called the Air Jordan 2009, the line’s twenty-fourth and now often labeled the Air Jordan 24, arrived in 2009 at a hundred and ninety dollars. After honoring number 23 with the XX3, Jordan Brand retired the numbering and named the next several shoes by year instead.

Designed by Jason Mayden and inspired by fencing, it introduced Articulated Propulsion Technology, a spring-like heel system developed with input from Paralympic sprinter April Holmes and the world of carbon-fiber running blades. The diamond-cut patent upper was unmistakable, for better or worse.

It is a polarizing shoe with a modest cultural footprint, and Jordan’s own site now catalogs its retros under the Air Jordan 24 name. It is the start of the brief year-named era, the most confusing stretch of the whole count.