Genuine OEM BMW emission control air pump hose, part number 11721742729. This hose is part of the secondary air injection system, transferring air from the pump to the exhaust manifold or catalytic converter to reduce emissions during cold starts. It is designed to withstand high temperatures and the specific pressures within the emission control system. Made from heat-resistant rubber or silicone materials. Genuine OEM hoses ensure the correct internal diameter, length, and routing for proper fitment and function, critical for emission compliance.