Directional adjustment mechanism for headgear of a respiratory therapy mask or interface

A headgear for a respiratory mask, the headgear comprising,

• a strap;
• a filament located at least partially within the strap;
• and
• a directional adjustment unit comprising:
• at least one movable frictional engagement member having an aperture forming a cavity extending through the at least one frictional engagement member, wherein:
• the aperture is arranged to receive the filament therethrough,
• the at least one frictional engagement member in a first configuration provides a disengaged configuration with respect to the filament,
• in a second configuration the at least one frictional engagement member provides an engaged configuration with respect to the filament, and
• the at least one frictional engagement member is movable between the engaged configuration and the disengaged configuration, and
• wherein the filament comprises a filament body having a substantially flat exterior surface portion extending along a longitudinal axis thereof, so that in the engaged configuration the substantially flat exterior surface portion of the filament body is brought into contact with the at least one frictional engagement member.