Some Lange boots, like the XT and XC series boots feature a ski-hike mechanism in the back of the boot.
Hike-Mode: Raise the ski/hike handle on the back spine of the boot and flex forward gently. The mechanism is now in hike mode, allowing the cuff to move backwards. To enjoy further cuff mobility, loosen the Velcro straps and move the cuff buckles to the extra-lateral ratchet hooks.
Ski-Mode: Put down the ski/hike handle and flex forward firmly until the cuff engages and you hear/feel a small click. Adjust/tighten the cuff buckles on the main ratchet and fasten the Velcro strap.