A face mask assembly for supplying breathable gas to a wearer, said face mask assembly comprising: a mask frame including a support, a facial cushion (16) attached to the mask frame, and a forehead support, said forehead support including: (i) a receiver (520) attached to the mask frame and comprising a slot on the upper side of the receiver, (ii) an elongated slider bar (622) which is received in the receiver and configurable between retracted and extended positions in a direction towards and away from a patients forehead with respect to the support, (iii) a forehead cushion assembly attached to a distal end of the bar, (iv) position markings (651) provided on the upper side of the elongate bar, and (v) an adjustment knob (550) retained in the slot of the receiver.
