Equipfit cast iron kettlebells are designed to provide a comfortable lifting experience both through handle grip and window size with durability being the most important design component increasing product longevity and safety for the lifter. Most kettlebells rattle or the handles break over time. This is due to the fact that the handles are typically welded on and fillers are added inside the unit to make a certain weight. Single casting overcomes these issues so you can buy and lift with quality reassurance and peace of mind.