Card lil helmet according to the principle of aerodynamics design the stereoscopic breathable air ventilation hole wind, lining using absorbent material, let refused to heat cycling process, at the same time equipped with insect nets, prevent mosquito to hinder rider a bike helmet, can effectively resist the part from the wind into the hole of the cool, keep the ride the walker's head temperature, avoid catch cold catch cold, lining and insect nets can be removed to clean, very convenient