The winter mushroom head, scientific name: high-flow air filter (Air Filter), because the shape looks like a mushroom growing in the ground, so commonly known as the winter mushroom head. It is installed in the engine air intake system in the mouth, it is by one or several clean air filter components of the assembly. Its main role is to filter out harmful impurities in the air that will enter the cylinder in order to reduce early wear and tear of the cylinder, piston, piston ring, valve and valve seat. Since the suction range of this air filter is different from that of a flat stock air spacer, it has the advantage of a larger intake flow rate, especially on vehicles that require more air intake for some turbocharged and mechanically supercharged engines. It is mostly seen in the power upgrade modification, in terms of air flow and other aspects, have a more outstanding performance than ordinary filters.