Features: 1. This product is just for single person to use, two person use is not allowed. 2. Before exercise, please check the hoop,handle and spring are in good condition. 3. Please use it far away from crowds, no less than 2m. 4. The rang of elastic tension: 150-160cm (Main spring together with handle) 5. Don't pull it quickly. You'd better to be slow in your movement, so that forge stamina effectively.