Our Trampoline is made of Steel pipe+PVC. The size is 40"D.Special tool is included for assembly. Thickened anti-slip rubber pads for protecting the floor and reducing noise. The fitness trampoline trains a wide range of muscle groups, helps build muscle mass, and strengthens the shoulder, hip, and leg muscles. This indoor trampoline is also the perfect equipment for losing weight. Please read the user manual or watch the installation video before installation. This fitness board installation process is relatively simple but requires some physical labor. It is best to install two people!