Sound-way Airport Bass Reflex Tube - Tube Diameter 70mm/Length 150mm, Black

Good quality bass reflex port. It happened to be exactly the right size and length for a project I had. Made of plastic but seems quite robust. It has fins around the end that goes onto the speaker baffle making the cut-out larger than it needs to be so I shave these down a bit to fit a slightly smaller hole. It is also slightly tapered so Its slightly wider at the flared end than the dimensions would suggest and very slightly narrower at the other end. Bass ports are a little bit of a black art so I was prepared to cut this down if needed - but as it worked out the length was perfect - I did some testing of the port frequencies with a signal generator. If it's the size you need then I would recommend.