Abstract: Adjustable boot - ski interface mechanisms for providing elevational adjustment of a skier's boot with respect to the ski and with respect to a separate, extraneous, releasable binding that is fixed to the ski, wherein the binding exerts a predetermined retaining force before releasing the boot from the ski upon occurrence of an external separating force when the skier encounters an obstacle which results in the latter force. The binding includes at least one of a front and a rear rest mechanism, secured to the ski for cooperation with at least one respective interface portion of the boot.