It is a tire equipped with a double protective layer against punctures, in total 4 mm of protection: a first layer of elastic rubber 3 mm thick as first protection against needles, thorns, nails, and a second protective layer of 1 mm in Aramid (Kevlar) as a last protective barrier if the blunt instrument should go beyond the first layer. These 2 levels of protection make the rubber practically impenetrable, making your bike rides safe and worry-free.