The main material of the bracket: aluminum alloy, iron, plastic Spring: Fiberglass Shoes bottom：rubber Bearing force specification: 70-90KG Net weight: 7KG Gross weight: 9KG Package: 88*29*39CM Instructions: 1. Beginners need to sit at a suitable height to facilitate buckling of the rocker 2. The straps that fix the feet on the foot pads should be closed. 3. Adjust the mounting part of the foot pad so that your foot is fixed in the best position, especially in the heel position. 4. Tighten the straps 5. If you wear the other, follow the same steps as the previous 6. You can stand against a wall or rely on the help of your friends 7. Beginners remember not to jump or stand on one leg 8. After sufficient exercise, start with simple jumps