Bintiva kettlebell weights are crafted from cast iron, and then encased in a vinyl coating that enhances the user's experience, and protects the surface of the exercise area. There is also a special protective bottom that ensures the user's ultimate stability and protection. The handle is not coated to avoid the stickiness associated with vinyl, the smooth metal handle won't stick to, hurt, or irritate the user's hands. The kettle weights are great for full body, body toning, and core strengthening exercises. The kettlebells are color coded by weight to make them easy to distinguish during a fitness program.