Caliper Buckle The micrometric closure called "CALIPER BUCKLE" is adjustable by lifting the central buckle. In order to completely open, lift together both side buckles, or push the center button to slightly loosen one tooth at the time. The system is also adjustable during a race. MTB Competition Sole Has been specifically studied for this specialty, may be fitted with two toe spikes on the front for traction in difficult and muddy conditions. The toe spikes are sold separately. Sidi Heel Cup Reinforced cup that stabilizes and supports the heel. Anatomically shaped plastic, reduces heel slip and provides increased power transfer. Provides additional foot protection in the event of a crash. Politex The "POLITEX" material is constructed of several overlapping layers with different physical-mechanical properties, the compacted PVC is then coupled to two fabrics (knitted fabric + felt) that is then is film dyed for long lasting color retention. "POLITEX" offers strong resistance to rip, laceration, streaching and fading. "POLITEX" is made in strict compliance with European regulations and is a totally green" product.