As to the question of rules regarding when and where peaceful protests may be held, that's highly dependent on the specific location of the protest.
The venturi mask, also known as an air-entrainment mask (and sometimes by the brand name VentimaskÂ®), is a medical device to deliver a known oxygen concentration to patients on controlled oxygen therapy.
The mask was specifically designed for compatibility with the subsystems of the AH-64, and it provides protection for the head, face, eyes and respiratory systems against field concentrations of all chemical and biological agents in liquid and aerosol forms, and against toxins and radioactive fallout particles.