Regardless of the weight of the kettlebell, it will retain the same dimensions. Due to this uniformity in appearance, the kettlebells are differentiated from each other by painting them different colors. The consistency in dimensions includes the ball of the kettlebell, the flatness of the base, and the handle diameter. Competition kettlebells are made of a single piece of steel; the variation in weight is determined by the size of a cavity in the middle of each kettlebell. They usually have squarish style handles that jut out vertically from the ball of the kettlebell.