Description Bellmouth Velocity Stack, 4 Inlet O.D. x 7 Bellmouth O.D. Material T6061 Aluminum Warranty One Year Limited Warranty Notes Specifications Inlet OD 4.00 (101.6mm)Bellmouth OD 7.00 (177.8mm)Compatible Air Filter 10960Vibrant Performance high efficiency Bellmouth-style Velocity Stacks allow for less turbulent air to enter your engine, resulting in airflow improvements and, ultimately, torque and horsepower gains. Spun from 1/8 (3mm) thick T6061 Aluminum Alloy