Bintiva dumbbell weights are crafted from cast iron, and then coated in a layer of non-slip neoprene, for added comfort, durability, and grip. The high quality neoprene is also made to protect the exercising surface, and other exercise equipment in the event that the dumbbell drops on it. The dumbbell ends are hexagon shaped, so that the dumbbell doesn't roll when not in use. The weights are great for body toning, and core strengthening exercises. The weights can be used while walking to add resistance so that more calories are burned. They are used in physical therapy, and will enhance any fitness, aerobics, running, or jogging routine.