Features 1.Through precision craft by many experts, such air inlet pipe is entitled with high performance according to strict rule. 2.With function mainly to pour the sound pressure of the airflow vibrating inside the box to the front and the sound pressure radiated from the front of the speaker, it can produce a bass effect. 3.Such a speaker phase-inverting hole is also called the sound tube and the air hole, and it is usually applicated in the inverted-phase speaker. 4.Its airflow is very smooth, obviously improving airflow sound. Meanwhile, it is suitable for 4-6 inches speaker. 5.It is made of ABS plastic material, and it is sturdy and durable. With smooth inner wall, and the flare ends are designed at both ends. specificationItem Type: Speaker air tube Total Length: Approx. 141mm / 5.6 in (As picture shown.) Speaker Housing Opening Diameter: Approx. 50mm / 2.0 in (As picture shown.) PackageList2 x Inverted Tube