Features: brand new and high quality Material: ABS thickened. Speaker inverted holes, also called sound tubes and air holes, are often used in inverted speakers, mainly to overwhelm the airflow sound of the speaker vibration in the box and overlap the sound pressure radiated in front of the speaker to produce a bass effect. Small opening: 50mm, generally used for 5-inch 6.5-inch speakers. Thickened ABS, styling features, flexible use. Thick ABS, shape characteristics, flexible use, solve the bass problem of small and thin speakers. Specifications: Material: ABS Color: Black Product size: diameter 54mm, opening 50mm Note: Due to manual measurement,please allow 0.5-3mm deviation. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! Package includes: 1 x Curved Shape Speaker Port Tube