Stylish Gymstick Pro Kettlebell is made of cast iron. Unlike traditional dumbbells, the Pro Kettlebells center of mass is extended beyond the hand. This makes swinging movements possible and because more muscle groups are utilized for swinging movement of the Pro Kettlebell than during the lifting of dumbbells, the overall workout is more effective. Available in 2kg, 4kg, 6kg, 8kg, 10kg, 12kg, 16kg, 20kg, 24kg, 28kg and 32kg.