The diameters of the interim pieces are always a little wider than the connectors, they have to fit to, to attach for example a transition clutch. It has exactly the same diameter as the tube-fan, so the both parts would lay edge on edge on one another. Due to the interim piece, they are connected.
To seal these connections you take a duct tape or a hose clamp.
|Product weight:||0,13 Kg|