A patient interface device (2,102) is includes a cushion (6,106) and a frame assembly (60,160) coupled to the cushion, the frame assembly including a main frame member (4,104) and a stiffening structure (62,162) coupled to the main frame member, the stiffening structure having a main arm (64,164), a first Y-portion coupled to a first end of the main arm having first and second front branches extending at upward and downward angles, respectively, from the first end of the main arm, and a second Y-portion coupled to a second end of the main arm having first and second rear branches extending at upward and downward angles, respectively, from the second end of the main arm.
