Round Protection DD stands for Double Defense. In addition to the RaceGuard protection belt, there is an effective fabric protection on the sidewall. Normally, the SnakeSkin fabric protection is used in the mountain bike sector. Excellent quality for intensive use. The double protection: High Density Guard and SnakeSkin. There is no better safety for lightweight off-road tires. Two different rubber compounds ensure better performance. One of the most effective inventions Schwalbe has ever made for mountain biking. A tire only becomes about 40-50 g heavier with the SnakeSkin fabric. This provides optimal protection against contact with sharp-edged stones, which can quickly slice open the sidewall of lightweight competition tires.