November 10, 2021 6:11 AM EST

When hardware engineer Aly Orady decided to lose weight, he devoured research about the science of strength training to figure out how to build muscles and shed pounds more effectively. His fitness journey led him to develop Tonal, a wall-mounted digital weight system that uses electromagnetic resistance rather than traditional metal plates, allowing users to change weight resistance with a tap on a screen. Tonal collects heaps of user data—about how much you can lift, at what pace and so on—to customize workouts. And unlike other high-tech exercise machines, it alters workouts in real time based on your performance, as a personal trainer would. That’s led athletes like Serena Williams, Stephen Curry, and LeBron James to sign on as endorsers and investors. All told, Tonal has raised about $450 million in venture capital and was valued at $1.6 billion in early 2021. Tonal costs $2,995 and requires a yearlong $49 monthly membership. —Guadalupe Gonzalez

Buy now: Tonal

More Must-Read Stories From TIME

Contact us at letters@time.com.

EDIT POST