Abstract: A flexible duct system has fittings connecting sections of the flexible duct which are pulled taut between adjacent ones of the fittings. A first fitting has a first end and a second end. The second end is distally disposed from the first end and defines a second terminal end and having a second end profile. A second fitting has a forward end and a rearward end. The forward end preferably faces toward the first fitting, spaced apart from the second end of the first fitting. The forward end defines a third terminal end and a third end profile. The rearward end is distally disposed from the forward end, and defines a fourth terminal end and a fourth end profile. The end profiles preferably each include a tapered surface and a catch shoulder. The tapered surfaces circumferentially extend around a central axis of a respective end profile and face in directions which extend outward of the respective end profile with the tapered surfaces narrowing in the respective outwardly extending direction.