86mm x 91mm Speaker Port Tube Subwoofer Bass Reflex Tube Bass Woofer Box 4pcs U-Joints 5 accuracy and fine-tuning function

5 accuracy and fine-tuning function

Insulatsion

wear resistance and high strength

Knobs Size: 18

Metal material stands up to outdoor use or indoor use whatever dry or wet

86mm x 91mm Speaker Port Tube Subwoofer Bass Reflex Tube Bass Woofer Box 4pcs U-Joints 5 accuracy and fine-tuning functionFeatures: Speaker Port Tube is used to improve the bass response of many types of speakers. There are plenty of types to help you with your vented box design, and carries tubes of every shape and size, including adjustable length ports and flared ports. These port tubes are a reliable, convenient installation, while at the same time providing a finished, "pro" look to your bass reflex speaker building project. Normal tubes suffer from nasty turbulence