Adjustment mechanism for adjusting length of a headband

An adjustment mechanism for allowing a user to adjust a length of a headband, the adjustment mechanism comprising:

• a stationary case defining an opening and a circular recess adjacent to the opening along a common axis;
• a clutch comprising:
• a cam arranged within the circular recess of the case and a pinion extending axially from the cam such that the pinion is positioned outside the case via the opening to engage with the headband, the cam having a first cam portion, a wedge portion, a second cam portion, and a tab arranged in a radially outward, sequential and repeated manner about the common axis;
• a roller positioned between the stationary case and the cam of the clutch such that the roller is located adjacent to the first cam portion of the cam;
• a knob having an actuating element, the actuating element positioned within the circular recess and arranged between the roller and the tab of the cam, wherein the knob is rotatable in:
• a first direction in which the actuating element is positioned adjacent to the second cam portion of the cam to allow the user to shorten the length of the headband by rotating the pinion in the first direction;
• and
• a second direction in which the actuating clement is positioned to frictionally engage with the stationary case and the wedge portion of the cam to allow the user to increase the length of the headband by rotating the pinion in the second direction.