Plastic 40mm Pre-Drilled InLine Coupling with Nipple – Pack of 10.
In order to connect silicon tip extraction hoses to the main ducting you need an appropriately sized nipple. These can be fiddly to fit in bare pipe as each one needs drilling and tapping before being screwed in.
To make things easier and quicker these 40mm inline couplings have the connection nipples already fitted. They are also push fit and made from rigid, injection moulded plastic so they are easy to fit and robust.