SIDI Crossair BootSPECS The lightest premium level MX boot available, size 9 = 3. 75 lbs. per boot Constructed of Technomicro Microfiber, which is lighter, more durable, and resistant to water than leather Flexibility and comfort out of the box Slim profile High wear rubber grip pad for control, with replaceable nylon wear pad on the medial side Flexibility and movement from two pivot points on the lateral and medial side work together Hyperextension and hyperflexion