Sidi Drako 2 with SRS Carbon Composite sole. Top model from Sidi. With the Sole Replacement System (SRS), it is easy to replace the treaded parts of the sole if these wear down. The parts are simply screwed under the bottom. The upper part of the shoe is made of Microfibra Techpro, which is a synthetic material that ensures a durable and breathable shoe. It is also water-resistant and environmentally friendly. Sidi has added extra protection on the heel and toe so that they keep their shape and thus help for a great fit. The shoe is closed by two Tecno-3 Push swivel buckles and a velcro buckle with security velcro. One swivel buckle is combined with a Soft Instep Closure system - 4. Soft Instep Closure system - 4 can be adjusted on both sides so that it sits comfortably over the foot. It can also be changed if the need arises.