The ventilation holes of the fiberglass safety helmet have been fully designed to prevent rainwater and foreign objects from entering. The shape and structure of the ventilation holes play a crucial role in preventing rainwater from entering. Many ventilation holes are designed with slanted holes or maze like structures, which make it difficult for rainwater to directly enter the cap through the ventilation holes under the influence of gravity. When rainwater falls on the cap shell, it will flow down along the curvature of the cap shell surface. Due to the special structure of the ventilation holes, rainwater cannot enter through the channels of the ventilation holes.

Secondly, the size of the ventilation holes is also precisely controlled. The aperture of the breathable hole is relatively small, usually less than 5 millimeters, which can ensure good breathability and effectively block larger raindrops from entering. Even if a small amount of small raindrops enter the ventilation hole, they will not directly contact the head due to the presence of the cap lining. Hat liners are usually made of materials with good water absorption, which can absorb a small amount of moisture and keep the head dry.

To prevent foreign objects from entering, it also relies on the size and structure of the ventilation holes. A smaller aperture can block most larger foreign objects, such as stones, debris, etc. At the same time, some protective nets or grille structures may be installed inside the ventilation holes to further block the entry of small foreign objects. These protective structures will not affect the circulation of air, but can effectively prevent foreign objects from entering the hat, ensuring the safety and comfort of users. However, under extremely severe weather conditions, such as rainstorm, sandstorm, etc., a small amount of rain or foreign matter may still enter, but it will not seriously affect the normal use of safety helmets and head safety.