3PCS GH127 80mm Hole Inverter Tubes Kit for 6.5-8 inches Speaker Ports Vent Connectors black

Feature: 1. Adopt high quality ABS plastic material, sturdy and durable, suitable for 6.5-8 inch speaker. 2. Environmentally friendly and safe, without any harmful substances, you can use with confidence. 3. Smooth inner wall design, with horn mouth design of the both ends. Smooth airflow, obviously reducing the sound. 4. The speaker phase-inverting hole, also called sound tube or air hole, is often used in the inverted-phase speaker. 5. The inverter tube is to pour the sound pressure of the airflow vibrating inside to the front, and overlap with the sound pressure radiated from the speaker to make a bass effect. Specification: @font-face{ font-family: Times New Roman ; } @font-face{ font-family: 宋体 ; } @font-face{ font-family: Calibri ; }