AS MUCH AS the running shoe industry has been obsessed with tech over the past half-decade, the types of innovations available to put on your feet aren’t always that exciting—or even obvious—at first glance. That’s not the case with On’s LightSpray tech, the robot-spun, silly string-like material that the Swiss brand has been showcasing at major running events since late 2024. The translucent, light upper is meant to stand out, even in a crowded field of lightweight, funky-looking kicks.