The ST draws its design from the off-road world, with the exclusive cam-lock buckle system integrated into a track-ready street boot. The dual-compound sole adds traction when you're off the bike. The ST is known as one of the most comfortable upper level street boots available. External nylon molded ankle brace system. Nylon inner sole with removable arch support pad. Dual compound sole. Sidi's exclusive cam-lock buckle system for easy entry and boot removal while still offering a perfect glove like fit. Bolt on replaceable, adjustable and aerodynamic nylon scuff pads on the toe. Technomicro is used as a base material. Double stitched in all high stress areas. Closable air vents on the foot outer. All bolt on parts are replaceable. An elastic panel adjacent to the entry zipper allows a bind free zip and improved fit. Lined with anti-abrasion Cambrelle in the foot area for comfort, the upper is lined with Teflon mesh which prevents complete absorption of water and sweat. These materials will not retain water or sweat on the inside of the boot. The boot will dry quickly. DuPont polymer toe shift pad. Perforated Teflon treated nylon lining. Replaceable, shock absorbing heel cup. The ST can accommodate riders with up to a 15-inch calf diameter 12.5 inches above from the bottom of their heel. Padded Achilles area.