Headgear with directional adjustment mechanism

A directional adjustment unit for a headgear for a respiratory mask, comprising:

• a movable frictional engagement member, the movable frictional engagement member having an aperture forming a cavity extending through the movable frictional engagement member, wherein the aperture is arranged to receive a filament of a strap of the headgear therethrough such that the filament follows a filament path through the directional adjustment unit, wherein the movable frictional engagement member in a first configuration provides a disengaged configuration with respect to the filament, and in a second configuration provides an engaged configuration with respect to the filament;
• the directional adjustment unit further comprising at least one filament guide configured to guide the filament as it passes through the directional adjustment unit, the at least one filament guide being configured to engage the filament to restrain the filament against bending of the filament in the directional adjustment unit at a location in which the at least one filament guide engages the filament;
• wherein the movable frictional engagement member is mounted on the directional adjustment unit such that the movable frictional engagement member can move relative to the directional adjustment unit along a predetermined elongate path which extends in a direction orthogonal to the filament path, when the movable frictional engagement member moves from the disengaged configuration to the engaged configuration;
• and
• wherein the movable frictional engagement member is configured to move rotationally from the disengaged configuration to the engaged configuration.