Made of solid cast iron, and coated with a thick layer of Ultra-low odor rubber. They are very convenient to use and store. Dumbbells can be used for a variety of exercises, they can be used for any multi-joint movement that targets major muscle groups of the body such as squats and chest presses. Ergonomic knurled handle for a comfortable and secure grip. The hex design eliminates rolling and makes for easy storage. Rubber coated dumbbells are way easier on your floor with its impact-absorbing properties, They can also resist cracking and chipping when set down heavily or dropped accidentally.