The Continental Gatorskin Tires use Duraskin anti-cut fabric to give the sidewalls extra protection against cuts. It's a polyamide (nylon) mesh that is bonded onto the sidewall plies. It acts like the ripstop material you'd find on ultralight jackets or tents.
In the event that you do encounter a sharp object with potential to cut the sidewall, the Duraskin mesh will resist and most importantly limit the extent of the damage. The second line of defense is a puncture resistant layer under the tread called Poly X Breaker. It's a dense layer of tough nylon, designed to add serious protection. With the tread and sidewall bolstered against the hazards of the road, you'll worry less about grit and gravel on the edge of the road and more about enjoying your ride.
Dual-layer puncture protection