SIDI Apex Boots Features Patented and trademarked Vertebra System protects the riders Achilles tendon Replaceable thermoplastic resin ankle ball protection cup Bolt on (not Velcro!) replaceable, adjustable and aerodynamic nylon scuff pads on the toe Composite inner sole Removable arch support Lorica outer construction Closable air vent Double stitched in all high stress areas All bolt on parts are replaceable Full length zip open entry Dual compound sole DuPont polymer toe shift pad Perforated Teflon treated nylon lining Shock absorbing heel cup