Rossignol liners offer a consistent fit across the full range of 97 mm, 100 mm, 102 mm and 104 mm internal lasts, as specific liners have been developed for each one. Every liner is designed for a particular internal last and boot construction - it is shaped to be a perfect match with the inside of the shell, which is especially important in terms of the length of liner in the toe box and heel retention. THERMO OPTISENSOR FIT LINER This new liner, used in Pursuit boots, is designed with - New materials giving better foot envelopment through better interaction between shell and liner. - A design incorporating envelopment zones at the instep and support zones at the heel. - New thermoformable materials enabling the boot to be customized to the individual skier's foot, for performance with comfort. This new liner is designed for optimal foot envelopment and feel, which improves performance and also gives an excellent "First Fit".