Package included 2pcs Speaker Cabinet Port Tubes; Material: Plastic | Dimension: 4” length with 2” diameter for installation & 2-1/2” out diameter | These Speaker Cabinet Port Tubes are ideal for building your own Speaker Cabinets or replacing old ones, which is an essential part of the Speaker Cabinet! | Used for improved speaker cabinet, portable speaker, home speaker or car speaker. | Add a really nice "bass reflex" effect to the built-in boxes in your speaker cabinet. Perfect for a subwoofer enclosure, speaker projects