The iron core part of the bell is made of high-quality ball milled cast steel, which has high strength and good wear resistance. The external rubber is made of natural neoprene, which is odorless, does not pollute the air, and has low elasticity. This protects the athlete from injury. And strong impact resistance, beautiful appearance, durable. It is suitable for ordinary training and has a novel structure, which is convenient, safe and stable to use.