A cushion member is for a patient interface device. The cushion member includes a body portion, a patient contacting portion, and a pre-stressed element located in at least one of the body portion or the patient contacting portion.

A method and an apparatus for manufacturing, in a continuous flow, face protection masks including a mask body and two U-shaped elastic thread portions, which are formed by bending respective elastic thread portions retained by a group of sectors including a fixed sector and two movable sectors rotatable with respect to the fixed sector.

A method and an apparatus for manufacturing, in a continuous flow, face protection masks including a mask body and two U-shaped elastic thread portions, which are formed by bending respective elastic thread portions retained by a group of sectors including a fixed sector and two movable sectors rotatable with respect to the fixed sector.

A hollow structure for a face mask includes an inner wall, an outer wall spaced from the inner wall to define a hollow area between the inner wall and the outer wall, and a bottom wall that couples the inner wall to the outer wall. A first portion and a second portion together define a closable opening into the hollow area. The second portion is coupled to the outer wall by a bi-stable membrane that allows the second portion to move between (1) a first, opened position in which the second portion is spaced from the first portion to allow access to the hollow area through the opening, and (2) a second, closed position in which the second position abuts the first portion to close the opening.

A method and an apparatus for manufacturing, in a continuous flow, face protection masks including a mask body and two U-shaped elastic thread portions, which are formed by bending respective elastic thread portions retained by a group of sectors including a fixed sector and two movable sectors rotatable with respect to the fixed sector.