On a recent Friday morning, a select group of Nike’s biggest fans got an alert. A new, limited-edition version of the brand’s Cortez running shoe–an old-school nylon sneaker originally released in 1972–was about to drop. The release was happening during the NBA All-Star Weekend in Los Angeles, and the shoes–red, white, and black, with the words “don’t trip” emblazoned across the laces–were made in partnership with rapper Kendrick Lamar, a local legend. Customers received the notification through an app called Snkrs, which Nike has been refining over the past year as a way of connecting superfans with desirable pairs of, you know, sneakers. It is distinct from the regular Nike app, where you go to get a pair of performance shoes. Snkrs sticks to the kinds of limited-edition runs–interesting colorways, unusual styles, partnerships with performing artists or fashion designers such as Riccardo Tisci–that are so popular they often end up being resold, concert-ticket-style, on the secondary market. Read more at Fast Company.