Neoprene coated with a cast iron core, the adidas 5kg Dumbbells help strengthen and tone. Featuring a unique hexagonal design, dumbbells stay put once set down for added safety and ease of storage. An established training cornerstone; dumbbells are built for both isolated and compound movements, allowing you to diversify your workouts and hit any goal. adidas 4kg Neoprene Hex Dumbbells in Black