The core function of a winter cold-proof and windproof head covering is to provide all-round warmth for the head, face, and neck, while blocking the invasion of cold wind and reducing body heat loss. It is an essential warmth-retaining gear for winter outdoor activities (such as cycling, hiking, and commuting). Its specific functions can be divided into the following points: 1. Core warmth retention: It covers parts that are prone to cold, such as the head (scalp except hair, behind the ears), ears, face (some styles expose the eyes/mouth and nose), and neck. This prevents these areas from direct contact with cold air, avoiding frostbite or headaches caused by cold. 2. Windproof protection: Most of the fabrics are made of windproof materials (such as nylon and polyester fiber coating), which can effectively block the penetration of cold wind and prevent sudden local temperature drop caused by "wind drilling". It is especially suitable for use in windy weather or high-speed sports (such as cycling). 3. Breathability balance: Most styles are designed with breathable fabrics/small holes around the mouth, nose, or behind the ears. This not only ensures warmth and windproof performance but also reduces the condensation of exhaled hot air into water (to avoid damp and cold face), improving wearing comfort. 4. Auxiliary protection: Some fleece-lined styles can enhance warmth retention, and some outdoor-specific styles can also slightly resist dust and snowflakes, reducing direct irritation of the external environment to the skin.