Inherent to the Genius Fit is Sidi’s renowned comfort and fit which has been frequently emulated by other shoe manufactures. Despite many attempts, only Sidi exhibits a truly slipper like feel due to the use of their highly breathable and durable Lorica fabric. Sidi’s Soft Instep Closure System and padded tongue provide an extremely secure fit without any undue pressure on the foot’s instep. Along with the caliper buckle, Sidi’s High Security Velco straps use interlocking polymer teeth to secure the foot without velcro slippage. To both protect the heel and provide further foot stability, Sidi uses a reinforced heel cup. Sidi’s heel cup, borrowed from their motorsport technology, is also designed to increase the shoes durability. New for the Genius Fit Pro, Sidi uses the Millennium 4 carbon composite sole which is 37% stiffer than the Genius’s previous nylon sole.