Our advantage: design with soft spikes, which increases comfort and training effect, ideal for rehabilitation exercises, hand strengthening. You can put the rope around your wrist so that the massage ball does not slip during training. 2 hardness levels: the grip balls have 2 ranges, 2.3 kg/5 lb for relaxation and beginners, 4.5 kg/10 lb for grip training and rehabilitation, you can train alone or involve family and friends in training. Good quality: the grip balls are made of high quality rubber (TPR) and retain their shape even with frequent use. All fingers can be exercised at the same time, durable and safe. Can be rinsed with water after use. GIFT CHOICE:The hand muscle trainer is lightweight and easy to carry. In addition to treatment, it can also reduce numbness and pressure on the hands, a good choice to prevent tension and relieve pressure.