Tennis balls didn’t get their distinctive neon hue until nearly a century after the game was invented.

In their bags, the dozen or so pink-clad women carried 500 pink and green tennis balls with the phrase “Ban Guns, Not Balls” written on them. They began tossing them to each other.

‘Challengers’ VFX supervisor shows IndieWire how they pulled off Luca Guadadigno’s vision of the camera and tennis ball becoming one.

Part of an international plan to save tennis—which has struggled to compete with sports like soccer, football and basketball—is introducing softer, lower-bouncing balls for kids.