The Dalbello Krypton Fusion I.D. boots are some of the most unique designs available today. Building off of their extremely successful three piece shell design (the tongue, lower boot, upper boot) the Fusion features a more anatomically correct shell shape than past Krypton models. Clocking in at a 120 flex rating, these boots are designed for aggressive skiers. This model comes equipped with an ID Intuition heat mold-able liner for that extra precise fit that is necessary for higher skiing ability levels. 98mm last:Forefoot width of 98mm for racing performance, not as concerned about comfort, although modern boots do a great job of keeping their performance boots quite comfortable. 120 Flex Rating:This boot is too stiff for beginners and even most intermediates. At this flex, the skier should be advanced to expert level, comfortable skiing at high speeds anywhere on the mountain. Cabrio Design:Dalbello\'s critically acclaimed 3-piece design is the cornerstone to their freestyle performance lineup. Cabrio boots secure the foot and lower leg in a comfortable way, with a smooth and progressive forward flex. Cabrio boots are great for helping fight against shin bang, and are easier to put on and take off than comparable (high performance, non-cabrio) boots. ID Thermo Intution Liners:ID Thermo liners are the lightest, warmest, and easiest Total Custom Fit inner boots in the world. ). Bottom line is these liners are basically THE best you can find.