Competition kettlebells are perfect for any kettlebell workout.Originally designed for use in Kettlebell Sport (or GS, short for Girevoy Sport), they are now commonplace in gyms across the country. Color-coded for easy identification, these bells meet legal Girevoy Sport Union (GSU), IKFF, and International Union of Kettlebell Lifting (IUKL) standards.Consistent sizing means consistent lifting with an ergonomic design for comfort. The 10KG - 32kg and the 48kg kettlebells have 60mm windows and 35mm for superior comfort, while the 4, 6, and 8KG bells have a 58mm window and 34mm handle, perfect for beginners. Gravity cast as one piece with no welding and a hollow core for an excellent surface finish and superior dimensional accuracy.No need to worry about the dreaded bell rattle-these babies will last you a lifetime!