The XT collection has all the great protective benefits of the original plus a new Omni-Heat™ reflective lining added to the inner boot. The XT offers only the best for the most extreme conditions. INSULATION: 400g. Removable 13mm ThermoPlus felt inner boot with Omni-Heat™ reflective lining. Color:Black, Red Quartz Shaft Height: 10 1/4 in. Heel Height: 1 2/9 in. Platform Height: 4/5 in. Calf Circumference: 15 in. Measurements based on size 1