To assist you in assembling the upper shells (front holes) of your KJ-XR3 and KJ-Pro7 models, there is specific hardware available. This hardware set consists of 2 bolts and 2 washers, which are designed to securely fasten the upper shells to the rest of the shoe structure. By using this hardware, you can ensure a reliable and robust connection for your Kangoo Jumps rebound shoes. Additionally, it's important to note that this hardware is also compatible with older models, providing versatility and convenience if you have previous generations of Kangoo Jumps rebound shoes.