The XMark Black Cast Iron Kettlebell improves flexibility and balance while providing a high intensity, strength training workout. Research shows a 20 minute kettlebell workout burns almost 300 calories. Each kettlebell movement engages multiple muscles due to the weight imbalance and the results are a combination of muscle-sculpting and heart-pumping cardio in one high intensity workout. With a higher intensity workout than standard weight training, kettlebell training with the XMarkBlack Cast Iron Kettlebell XM is one of the most effective weight training workouts for burning fat, losing weight and building muscle. Swing, curl and lift your way to an amazing body with XMark, the mark of excellence.