These boots were for flying extremely fast at 2,100 MPH for SR-71 Blackbird aircrew. As the fastest jet in the world there was a lot of specialized aircrew flight equipment including the 'spurred' #shoes. If the aircrew had to eject, the restraint systems in the plane would pull the crews arms, legs, and feet to the ejection seat immediately prior to eject. The spurs are part of the system to lock in and keep limbs from flailing. I took this photo at a friends personal museum when I hand delivered an autographed Blue Angels flight helmet for museum display. Pretty intriguing to see a little piece of high-flying, fast moving, aerospace history.