Shell: high quality ABS SHELL, and resistance to penetrate, impact resistance. Buffer layer: high-density EPS foam Lined. Lining: high-grade COOLMAX, deodorant, absorb sweat. Suggest size:M(55-56cm), L(57-58cm), XL(59-60cm).Please make sure it is correct. We guarantee all our customers would be satisfied with our products. Your 100% satisfaction is our goal.