The Mishimoto N52 silicone intake boot is constructed of five layers of silicone with steel reinforcement rings for maximum durability. The steel reinforcement rings keep this hose from collapsing when under load, keeping your engine supplied with adequate airflow. The stock N52 intake boot has a resonator that BMW included to keep the N52 quiet. We tossed that resonator to the curb for a nice increase in engine and intake tone. This N52 intake boot fits with the stock airbox and single stage or 3-stage intake manifolds. The silicone construction will provide you with a long service life, and the Mishimoto Lifetime Warranty will make sure your intake boot is always leak free!