The Laerdal Pocket Mask?s design, filter and one-way valve make it a quality choice that provides protection during CPR. By creating a slight distance between the patient and care provider the Pocket Mask also makes seeing patient lip color and chest movement easier. A high-quality 3M Filtrete hydrophobic filter under a one-way valve filters out contaminates in the air being transferred between the care provider and the patient, protecting them both.