A sport footwear includes at least an upper part configured to act as an upper cuff and a lower part acting as a lower shell. The upper part has a pair of opposite and distanced lateral edges. At least one terminal closing mechanism is provided on the lateral edges and at least one other closing mechanism, positioned adjacent to the terminal closing mechanism, which extend frontally astride the lateral edges. The sport footwear includes a single command mechanism configured to drive both of the closing mechanisms at the same time. The command mechanism includes at least one main lever pivoted on a first of the lateral edges. Moreover, the closing mechanisms are each provided with a respective drive end connected to the main lever, near the first of the lateral edges, and with an opposite anchoring end connected to a second of the lateral edges.

A ski boot includes a substantially rigid foot-casing that accommodates a user's foot; a substantially rigid cuff enclosing the lower leg of the user and hinged to the foot-casing for swinging about a first rotation axis substantially perpendicular to a midplane of the ski boot; a protective innerboot within the foot-casing and adapted to accommodate the user's foot; and a manually-operated cuff closing assembly adapted to tighten the cuff on the user's leg, and in turn includes: a manually-operated tensioning device rigidly fixed on a first lateral side of the cuff; a flexible ribbon having two ends rigidly fixed to the second lateral side of the cuff opposite to said first lateral side, and extends grazing the front part of the cuff up to the tensioning device; and a coupling member is fitted in free slidable manner on said flexible ribbon, to couple in releasable manner to said tensioning device.

In a tensioning device for adjustably varying the perimeter or receiving volume of a ski boot, and a ski boot with such a tensioning device, the tensioning device includes a support plate to be fastened to the ski boot. The tensioning device further includes a winding device with at least one spool for the winding in and out of at least one tensioning cable as needed, wherein the winding device is fastened to or is fastenable to the support plate. The support plate has at least one fastener that is configured to be connected with at least one corresponding anchor on the ski boot, wherein the at least one corresponding anchor on the ski boot in an alternative use is configured for the fastening of a lever-operable tensioning buckle to the ski boot or for the fastening of an associated component of a lever-operable tensioning buckle.

Tightening strap for ski boots adapted to be wound in a loop around the cuff of a ski boot to tighten said cuff on the user's leg; the tightening strap comprising an oblong flexible element, which is adapted to be wound around the cuff and includes at least one elastic member with auxetic behaviour formed by an oblong plate-like body, which has a monolithic structure and is divided into a plurality of contiguous flat sectors, each of which has a macroscopic reticular structure with auxetic behaviour, which structure is capable of stretching and, at the same time, also of widening in elastic manner when the oblong plate-like body is subjected to traction, and also differs from that of the adjacent flat sectors.