Description Bellmouth Velocity Stack, 3.5 Inlet O.D. x 6 Bellmouth O.D. Material T6061 Aluminum Warranty One Year Limited Warranty Notes Specifications Inlet OD 3.50 (88.9mm)Bellmouth OD 6.00 (152.4mm)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.