Velocity Stack Filter for 3in stack. Condition is New. This product by B&B Performance Engineering is designed to help filter air coming into velocity stacks. These are ideal for shows and street to keep rocks, debris and particles out of your engine extending the life of your motor. These stacks are completely custom and can be made any way, if you would like a different design please contact us. 3364575675. Stacks do NOT come with filter material because the material needs to be specific to the engine, tune and use, but we can order material for you.