Free Tracker Bindings: Don’t let the excitement of free bindings prevent you from getting the size you need! If you have a boot sole length of 265mm-320mm, you want to go with the “S” aka small binding. Anything 320mm’s and up would require the “L” aka large option. The 100mm,115mm and 130mm is in reference to the brake width to fit the width of your skis.
Adaptive Fit Last 102mm-104mm: Head's newest boot technology is called Adaptive Fit. The Adaptive Fit boots essentially have two lasts, one at 102mm and one at 104mm, and all it requires is the turn of a screw.
90/100 Flex Rating: This boot has an adjustable flex, which can be set as stiff as 100 and as soft as 90. 90-100 flex boots are best for upper intermediate to advanced skiers, or even experts who are more concerned with cruising comfort.
Tri-Injected Energy Frame Shell: Most ski boots are Bi-Injected into the mold to create two different densities of plastic. Head went ahead and did one better, tri-injection molding. This means there are three levels of plastic density instead of two, meaning the transition from the stiff/dense sole of the boot to the lighter upper-cuff of the boot is more fluid. This in turn makes your skiing smoother and the boot has a more predictable flex throughout all parts of the boot.
HeatFit/High Performance HeatFit Liner: Self molding inserts in the liner and tongue quickly adapt to the shape of your feet, just by wearing and skiing them.
Soft Walk Heel: A rubber insert in the heel cushions while walking to get better grip and a more comfortable stride.
Macro adjust ladder (SuperMacro): The tooth plate opposite the top buckles can be moved in or out for a huge range of adjustment, and to fit narrow to wide lower legs.
35mm strap: Wider than average strap at the top of the boot to help keep the boot together and to give good performance while skiing.
Double Canting: Two adjustment bolts, one each side of the ankle, allow for maximum adjustment for leg/knee alignment problems. The alignment of the boot cuff helps the skis stay flat on the ground while you are still bow-legged or knock-kneed.
Replaceable Toe and Heel Pads: This is a must-have for skiers that don't live in ski in/ski out condos. When your ski tech tells you that you have to buy new boots because the soles are worn down too much, just laugh at him and tell him to order you a new set of sole plates.
Double Power Buckles: Some of the buckles on this boot (usually the top 2) have a metal flip-out that can be extended to give the skier more leverage when clamping it down.
Spine-Tech Buckles: The Spine-Tech buckle features a closure point that stays in place (it looks like a spinal cord). It increases overlap in the shell flaps which brings the boot closer to your leg and reduces pressure points that are usually caused with traditional buckles.