A fastening device for ski boots. The device has a control means, an adjustment means and a strap assembly. The control means is operatable by a user and drives the adjustment means, which is coupled to the strap assembly. The adjustment means includes a gear set and a threaded rod, which allows for a very fine adjustment of the strap assembly and as a result a very fine adjustment of the fit of the boot on a skier's foot. Magnets may also be provided in the control means in a manner that allows the control means to maintain its position.