bintiva Kettlebells - Professional Grade, Vinyl Coated, Solid Cast Iron Weights With a Special Protective Bottom Bintiva kettlebells are crafted from professional grade cast iron, and encased in a protective vinyl coating to protect both the user, and the exercising surface. A special protective bottom ensures stability and safety. The weights are color coded by weight to make them easy to distinguish during a fitness program. The handle of the kettle bell is not coated to avoid the stickiness associated with vinyl. Adding kettlebells to a fitness routine enhances muscular strength, while burning calories, and is ideal for body toning and core strengthening exercises.