Abstract: A flexible connector for flat wall sheet metal ducting comprises an elongated sleeve duct of rectangular cross-section and a pair of connector ducts, each having an end portion telescoped into an end portion of the sleeve duct with the walls of the connector duct in widthwise parallel inwardly spaced relation to respective walls of the sleeve duct. A resiliently compressible gasket is secured in the sleeve duct near each end thereof, surrounding and compressed against the adjacent connector duct, which is slidable in the gasket so that the sleeve duct can swing in a pair of opposite directions relative to the connector duct. Each of a pair of opposite walls of each connector duct has an exterior surface defined by a false wall which is arcuately curved along its length concentrically to the axis about which the sleeve duct swings.