Abstract: A single piece duct fitting of generally cylindrical configuration for attachment to a large cylindrically-shaped flexible duct having a curved, easily deformed sidewall in which a hole has been created. This novel duct fitting is constructed of deformable sheet material that, before being assembled into a cylindrical configuration, was defined by an elongate sheet of material having a long edge of a generally sinusoidal configuration, with a plurality of short lateral slots defining teeth in this long edge. A pair of relatively closely spaced curves of generally sinusoidal configuration are disposed adjacent the teeth, which curves bear a closely aligned relationship with the first long edge of generally sinusoidal configuration. A plurality of evenly spaced slits extend between the pair of sinusoidal curves, with these slits defining a plurality of substantially identical tab members intended to bend outwardly when lengthwise compression is applied to the duct fitting.

Abstract: A duct fitting of generally cylindrical configuration for attachment to a relatively large, generally cylindrically-shaped flexible duct having a curved sidewall of easily deformed material, in which sidewall a hole of particular size has been created. This duct fitting is constructed of deformable sheet material and has first and second open ends, with the first end having a curvature conforming to the configuration of the curved sidewall of the flexible duct. The second end of the duct fitting is adapted to receive thereon, a relatively small branch duct to be connected in a leak-free manner to the flexible duct. In accordance with this invention, the first end of the duct fitting has a plurality of short, lateral slots disposed at spaced locations around its circumference, thus to define a plurality of bendable teeth arranged in a non-planar array.