Depends on the model, but they are a full custom fit liner, and the gold as found in the pro I.d. Is a wrap liner, which promotes better energy transmission to your boot. They are made mostly of closed cell foam, which is found in small amounts in stock liners, which means very little packing out, it also means a warm liner, as closed cell foam retains heat better than open cell. The liners though do take up more room in the boot, effectively narrowing the boot significantly. Please, if any of this info is wrong, correct me.