This article originally appeared on InStyle.com.
Khlo Kardashian is no stranger to the gym. You’ve probably seen the 32-year-old star running drills and lifting heavy weights on social media. But there’s one specific gym tool that she praises for transforming her stomach.
“Don’t ever do another situp again, honey,” Kardashian explains on her website and app. “There are way more effective moves for toning your abs and strengthening your core while torching major calories. All you need is a BOSU ball.”
If you have no idea what a BOSU trainer is, it’s that blue piece of equipment that looks like a fitness ball cut in half. You may have seen gym goers using it to intensify lunges or make their squats a bit more challenging. The unstable surface strengthens muscles in a way that flat surfaces can’t compete with. That’s why it has become a favorite amongst stars like Kardashian.
BOSU Balance Trainer
The best part about a BOSU ball is that they don’t take up too much space, and it’s much more affordable than complex fitness machines. The one above comes with a workout DVD and a pump to inflate the ball for only $88.
If you have Amazon Prime, you can get it two-day shipping for free (because summer is here). So you might as well grab one to keep at home for those moments you don’t feel like going to the gym.