These kettlebells are made of solid cast iron and then dipped in vinyl for increased durability. Kettlebells have become one of the most popular trends on the health club scene. On any given day, you can see everyone from housewives to celebrities to business executives or professional athletes and trainers performing the most advanced kettlebell routines with perfect form. Now thanks to Body-Solid, you can enjoy the many benefits of kettle bell training in the comfort and convenience of your own home.