33-3051 is an original position-replacement trapezoidal flat high-performance air filter. It is specifically designed for multiple sedans / coupe models of the BMW F chassis series (mainly including 3 Series F30, 4 Series F32, 2 Series F22, and 1 Series F20). It is directly installed in the original factory air filter box without the need for additional modifications. It offers both power enhancement and long-term filtration protection, suitable for urban commuting, high-speed driving, performance-oriented driving, and daily household use scenarios. It is compatible with the original factory ECU and emission system, complies with the requirements of 50 US states (CARB certification compliant), and does not affect the original vehicle warranty.