Abstract: A tubing assembly for use with a patient interface device in delivering a flow of breathing gas to an airway of a user is provided. The tubing assembly comprises a manifold portion structured to be disposed generally atop the user's head. The tubing assembly further comprises a plurality of tubular portions. Each tubular portion extends from the manifold portion to a distal end. Each tubular portion is structured to communicate the flow of breathing gas from the manifold portion to the patient interface device. The tubing assembly further comprises at least one adjustment unit configured to adjust a length of a corresponding tubular portion from the plurality of tubular portions. The at least one adjustment unit comprises first and adjustment members that are movable relative to each other, and are selectively and releasably locked to each other at a selected discrete position from a plurality of discrete positions.