These don’t come stock in boots, they’re added to boots by fitters….. aside from what was stated above, they can also be used to create the illusion of having a bit more room in the toe area. It pulls the foot up and therefore away from the front, as well as used to raise a skiers calf higher above the liner if they feel that the upper of the boot is too tight (higher up means that the boot would close on a narrower part of the lower leg).