The gym gear rubber dumbbells sets are made with a steel core coated in rubber these weights are maintenance free and won t damage the floor if you drop them on it within reason these should last longer than any other dumbbells these dumbbells should never get lose or need tightening when users bang the weights together or drop on they will not make lots of noise or damage the weight key features of the gym gear rubber dumbbells sets strong and durable will last longer than any other dum