Changying Sporting Goods Co., Ltd. is a company specializing in the production of small sporting goods, and is also the governing unit of Zhejiang Cultural and Sports Miscellaneous Products Association. Shuanglin belongs to its brands, and the most famous product is Shuanglin arm force. It has focused on the research and development of arm force devices for 18 years, and has a number of arm force device patents, and the annual sales volume of offline arm force devices alone is as high as 600,000. Shuanglin arm force device adopts stainless steel spring, which has strong elasticity and built-in safety spring to ensure the safety of use. At the same time, the spring can be bent at least 10,000 times, which is twice the service life of the general arm force device, and it is very durable. The handle is made of PPR material, which is comfortable to feel and sweat-wicking and non-slip, which further enhances safety. The price is moderate, starting from about 35 yuan, with high cost performance, and is suitable for a wide range of people.