It doesn't have the black-diamond rigidity of Salomon's top performance boots but the Performa 4.0 does have the exceptional flex and fit features for comfort-seeking skiers who insist on nothing less. Salomon recently revamped their Perfect Fit in all of their boots but the Performer liner received more space--3 millimeters--and more room to move around in the liner with a plusher (4 millimeters!) sole. If you're going to wear a ski boot all day and you don't require the extra rigid structure for navigating moguls and broken crud the Performa 4.0 is your equivalent to a bedside slipper--especially if you want a ski boot that's easy to slip into. The flex rating is a moderate 55 so you have enough stiffness for those occasional black diamond runs but the Performa 4.0 really delivers if you're intent on cruising the blue runs all day long.