Please note that these insoles need to be custom moulded, shaped and ground to fit using machines that we have in our Snow+Rock stores with boot fitting locations. This cannot be done at home.When paired with Sidas Heel Stabilizers (sold separately), these Sidas Winter Custom Ski Insoles provide you with maximum performance, for skiing and snowboarding. The Winter Custom Ski is a flat insole, 100% customizable to the morphology of the foot, thanks to the Custom technology, by thermoforming. This customization can be done only in Snow+Rock stores, to take the fingerprints of your feet. Built for sports veteran in search of a 100% made for you and for your sport.